This is tricky. If it is a muscular imbalance J bands are awesome (DD did them religiously) but if a muscle is pressing on a nerve or artery any kind of PT can cause more issues. PT can also move the muscle off the nerve or artery but it's tricky in a lot of cases.DD had something similar. She is 15 happened between school ball and the summer travel season. She had taken a few weeks off from pitching and was lifting her typical 4-5 days a week during her pitching break. We pitched for a few days and her glove side shoulder really bothered her. As we started looking at it and feeling around it was a muscle that knotted up behind her shoulder. We hit it with the massage gun and heat. She also spent time in the hot tub, and 2 days later she was good to go. Her glove doesn't swim anymore so like you we were able to rule that out. We always use j bands to stretch. However we were not disciplined, following that incident we use them every time we pitch before and typically 30 min after.