Are you sure it isn't RSD/CRPS? Has that possibility been mentioned?
It can occur after a surgery or even a minor injury.
We have a RSD/CRPS forum for more info about it.
Reflex Sympathetic Dystrophy (Complex Regional Pain Syndromes Type I) and Causalgia (Complex Regional Pain Syndromes Type II)(RSD and CRPS)
http://neurotalk.psychcentral.com/forum21.html