Well I don't know for absolute certain without the aid of an ultrasound machine, to perform a noninvasive examination but my Dx would be plantar fasciitis, which is inflammation of the plantar fascia, a band of connective tissue that runs along the heel and quite a bit of the underside of the foot, its tendon-like tissue, so sort of tendinitis-like, and I know all too well what THAT is like, and it is NOT pleasant (as a kid I fell on a piece of glass that was sticking upwards and the big piece of...well..I assume it was a broken windowpane, bloody big, jagged evil bastard thing went straight through my patellar tendon (the one that passes over the little gap you'll feel if you press gently below your kneecap bone itself and allows movement), had to break a large piece of it off since I couldn't remove the entire thing, just so that in the several mile (for your average person who hasn't just fallen with their full weight on a glass spike through the knee joint, its quite a lot more for somebody who has done just that, especially a little kid) and I've had a rotten case of tendinitis there ever since, which is really, really painful, in addition to joint damage from where it actually went IN the joint cavity itself (thats the reason I take a lot of pain meds, that and over time, to compensate for the way I could no longer bear weight, I unconsciously changed the way I walk, to lower the weight put on that knee and tendon, since for many, many, many years I got no pain relief whatsoever, they just told me to either take paracetamol, which I don't respond to at all for pain, or to take oral non-steroidal antiinflammatories, which I can't, because it'd probably end up with a GI bleed, ulcer or some similar nastiness since my stomach is so messed up I'd not dare take oral NSAIDs) so I coped the only way I could, which was to alter my gait, which was largely unconscious as an act, over time that caused trochanteric bursitis both sides.
Shortly after recovering from the knee thing I was attacked in the street by a bunch of way, way older chavscum, a lot of them, and got my damaged knee stamped on repeatedly. (along with my head and too many other bits to think of) and got left with tendinitis for the rest of my life. Its really, really not a nice thing.
So with the foot, most likely its plantar fasciitis, possibly with a calcaneal spur (a bone spike growing out of a part of the calcaneal bone (the heel), that last is a guess based on percentage probability.) It is as likely to be the case as not the case, given the probability of calcaneal spur in cases of plantar fasciitis is around 50%, so assuming my initial diagnosis of plantar fasciitis to be correct then the probability of having such a spur is more or less a flip of a coin.
Weird thing is, that usually plantar fasciitis is caused by things like sports injury, massive exertion, certain antibiotics (fluoroquinolones) can actually cause tendons to spontaneously rupture, which is even worse, makes them literally burst, reportedly one of the most agonizing things that can happen to a person who is born with the capacity to feel pain [congenital total inability to feel pain exists], or caused by exercise (plantar fasciitis, not tendon rupture), and given how limited my mobility is now, I can just about go to the shop closest to my house without getting driven there by my old man, or get to my DR surgery if I take the bike) but otherwise I've not PUT any exertion onto my feet, I'm more or less stuck lying on the sofa, flat, with my back propped up with pillows, rolled up coats etc.) I get up when I have to go from the lounge to the bog, since that cannot be avoided, or to get myself food from the kitchen, and after taking a hefty dose of painkillers sufficiently often to keep a given amount of pain relief enough to let me perform the task/s I need to perform, to go to my lab and do the things I have on my list of things to do in there.
Even with the pain meds, I'm still in constant pain. Due to (FINALLY) see a pain clinic, with doctors who have made pain control their specialty. You know you might think I'm a junkie, but some people do have a reason to take such meds, on prescription. And I've been without, for a long time. I couldn't play sports in school, I couldn't run...well..sort of...I CAN perform the action but afterwards I'll be bedridden for days. And I CAN'T do vigorous exercise, mostly, I'm stuck, lying down. If I HAVE to do something, then I'll take a large dose of pain meds, and suffer the consequences, moderated with lesser doses during the recovery phase.
(yes, I will enjoy large amounts of pain meds, they cause euphoria, but if I need to take the dose anyway, I see it as illogical to take any measure such as would make me feel shitty, if its going to make me feel good as a side effect I figure I may as well enjoy it while it lasts, after all, why not? its not like I am going to learn something like buddhist meditation aimed at divorcing oneself from pleasure. If its gonna feel good, I'm gonna let it do so.
But for a long, long time, I have to spend most of my day and night lying down, but even stretching my legs out and having my heels touch anything, a cushion, my bed covers (well, sofa with a duvet over it. then within a few minutes my heels start getting that white-hot-rusty-nail hammered in through my heels sensation. So I have to stick a cushion under my lower calf muscles to make sure my feet do not touch anything, I can stop the pain without meds, by using the strength of my back and core muscles to elevate my legs completely off any surface, but I can only sustain that for a couple of minutes at most before I can't hold the position any longer)
Didn't help that I once accidentally took a 40-50 foot drop off a large wall which unknown to me, wasn't a wall, but a railway parapet, after I got chased (I'd done nothing at all to the pricks to deserve it) by a bunch of drunken chavscum thugs screaming for blood and quite obviously wanting to rip me limb from limb as 'entertainment'. Too many of them to fight and win, so as they came cannonballing toward me out of the pub they had been infesting, so I ran like hell in the other direction, thinking to run on adrenaline for a few moments enough to get me out of their targeting, meaning to deal with the pain later. Vaulted what I thought was a wall, but it wasn't. It was the thing stopping people walking on the street from dropping off and splattering myself.
To my great surprise, after landing on a load of railway ballast stones, bricks and other things you don't want to fall that far onto, and not only survived the landing, but actually got up, after recovering from beingsomewhat stunned from smashing down onto lots of stones and bricks and shite, but rolled through a load of nettles and bramble-thorn thicket before whacking myself on the railway tracks, sore as hell of course, and ripped an entire collection of new arseholes by the being catapulted through the thornburshes, but not a single broken bone.
But it sure as fuck didn't do my knee any good either. Also had surgery on the knee, that failed, was meant to remove little sharp bone fragments from the tendon, but just caused worse joint damage and tendonitis, as well as inflicted a load of nerve damage through that leg, that left me without much feeling in that leg, other than neuropathic pain. (nerve-damage-induced type of pain is well known to require non-opioid type painkillers if much is to be done about it, since neuropathic pain response really poorly to opioids, they aren't very effective)
