This can be a case of tendinitis, which is caused by inflammation of a tendon. Treatment can range from resting to the use of non-steroidal anti-inflammatory drugs. Physical therapy is often recommended. Consult a physician. http://en.wikipedia.org/wiki/Tendinitis has more information.
Probably, a bad thing, nerves are getting pinched, usually associated with carpel tunnel, you on a keyboard, bar tend, waitress, crochet, etc., so see a doc. and easy up on the cause, or readjust the way you hold it, some ibuprofen,cold pack then hot pack, rest,