My 13 yr old is a baseball pitcher, last yr. he pulled something in the tricep area, took him to the doc, pulled muscle(?), just started again this yr.............and already he has pain from his armpit to his elbow, any ideas on what it could be and what I can do for him, no swelling or bruising or anything of that nature, just pain during that pitching motion and when he stretches out..........thanks in advance...............