My head doesn't feel right.
In what way? 
My head doesn't feel right.
Aside from, "You have a hole in your mind," what else is gong on?
For a while now, I've been getting an itching/burning sensation in a specific region in my head when I take dexamphetamine, and I can sense that parts of my brain aren't functioning properly; it's like there's a few instruments missing from the orchestra of my mind, and although the music is playing, I can tell that it's incomplete. I'm used to experiencing a wide range of mental states, and even before I started taking dexamphetamine, those brain regions had a tendency to slip into a dormant state or explode into hyperactivity for days, weeks or months at a time, but the dexamphetamine seem to be directly suppressing them at the moment. Taking a break from the dexamphetamine has the effect of reactivating the problematic regions, but also decreases my overall alertness and causes me to sleep excessively, which is another problem that I've had since before I started taking dexamphetamine. Caffeine also tends to give me unpleasant sensations in my head and shuts down certain brain regions with long-term use, but the onset is more rapid than has been the case with dexamphetamine and it's easier to take long breaks from caffeine when I need them.
I'm waiting for an appointment to have a sleep study done at the hospital, to investigate why I have difficulty staying awake. I'll have electrodes stuck to my head and I'll have to stay in a room at the hospital for 24-48 hours, but if all goes well, I'll get put onto modafinil, which hopefully will keep me awake without the side-effects and creeping tolerance issues of dexamphetamine and caffeine, and I won't have to choose between the orchestra playing with a few missing instruments, or playing with a full compliment but only for half the show.
ponds from now on.