Hi George, it seems like it could be a muscular issue but then I would not rule out the joints such as the AC joint and neck as well. You really need to drop into a sports physio clinic and show them how the injury occurred and get them to make a manual assessment. Perhaps this could be assisted with an ultrasound scan or MRI but an assessment and some rehab advice following would be a worth while first investment. Unfortunately the Dr is not the one for this type of assessment.