That really sucks.
Have you been to a doctor and gotten xrays yet?
That'd be the next step just to be sure you don't have something visibly wrong. You might have to go take some physical therapy or something too.
Last but not least... Tylenol 3's work wonders.
Can't remember if anybody suggested it but do a bunch of research on carpal tunnel syndrome and see what info you can find.
Hell... last thing ya wanna do is give up guitar if you can help it.