Don't wait too long, the damage could become severe. I know a lot a guitar player (myself including) who had at some point tendon problems. If taken early they are easily manageable.
If you go see the Doc make sure he tries to identify the source of the problem. it might not even be related to the guitar. The guitar might have put more stress on a already existing condition. Threat the injury, find the source, correct the source, live happily ever after ;)
Keep us posted.
