HELPP

so around my shoulder blade area and farther down but not near my kidneys, it hurts so bad that I can barely move. I have a heating thing on it to relax the muscle/area and I have no clue what I did. it started hurting yesterday but Friday I played really intense tug a war at my school pep ralley(we won✌🏻️🔥💁🏼) so help me out? I might go to the doctors if doesn't get better by tomorrow