Don't overlook environmental allergies. I get those - bad. Weather changes, wet leaves and grass...oh man, my head feels like it wants to explode. The headaches, can't sleep, food doesn't taste right, lethargy...the whole thing.

You might want to look into CFS / Myalgia as well. My one sister has CFS and she describes a lot of those same symptoms that you have. (CFS: Chronic Fatigue Syndrome)

Good luck. Hope you feel better soon. It stinks to be ill. I know, I've been battling some horid, mutant alien flu this week. My body has been producing things that are not of this earth when I cough or sneeze. Eww. Nasty business. :)