The extreme tenderness & hypersensitivity might be fibromyalgia or possibly RSD -also called CRPS???
but I'm totally guessing - it could be other things also, but those are ones I've read about more on the forums here.

I'm sure they checked your thyroid with the blood work, it can cause increased pain /symptoms if imbalanced.

Another thing to look at might be chronic myofascial pain (CMP)
http://homepages.sover.net/~devstar/define.htm

Fibromyalgia and Chronic Fatigue
http://neurotalk.psychcentral.com/forum12.html
Reflex Sympathetic Dystrophy (RSD and CRPS)
http://neurotalk.psychcentral.com/forum21.html
TOS forum useful sticky thread-
http://neurotalk.psychcentral.com/thread84-3.html