I've had to deal with a lot of chest pains and never really found the true cause. I've had to go to minor emergency clinics for EKG's and such several times. I even went to a heart doctor. All test results always came back normal.

You're very young so try not to worry too much about it. I always think that a trip to the doctor never hurts though!

Maybe you pulled something? See if a heating pad helps the pain. If it does, its probably just an injury.