if they didnt give you one and its still super week and giving you problems, ask your mom if you can set up an appointment with the family doctor, go see him, tell him whats wrong, and he should set you up with a therapist that he thinks is suitable.
you can do this your self if you have one of those resistance bands(maybe your mom has one)...anyways...take it and tie it to a bed post or something, put your elbom at your side at a 90 degree angle and slowly rotate it in a 180 degree motion. this will work out your rotators cup. then take it and step on the resistance band, and straighten your arm, bring it staight up out to your side, do reps of that. then do it bringing your arm out in front of you.
just do various assortments of those...start out with a little resistance then move on to more difficult stuff.
hope it helps and that you get what i'm talking about. haha. its hard to explain