Have you tried glucosamine sulphate, Rage? I've used it when I was having a lot of knee pain, and it helped — not a lot, but enough to make it worthwhile.
I know this is going to be controversial, but here goes: About 10 years ago, a friend came to stay with us who was a complete vegan. No animal products, not even honey. I adopted the same diet for about 6 weeks, just to see what it was like. All my chronic muscle and joint pains, including back pain, disappeared completely. My cholesterol also dropped, and my blood haemoglobin actually went up (must have been all the broccoli).
I wasn't able to stay vegan after the friend left. Dammit, I loves me some red meat, and am fortunate to live in a country that has a plentiful, cheap and tasty supply of it. But if worse comes to worst, it could be something for you to experiment with.
Oh and also, I consulted several orthopaedic surgeons before finding the one who performed the surgery that fixed my knee problem. Two of them were total assholes. Keep trying until you find a doc that will help you.