What I learned is that the shoulder is a very complex joint, not really a ball and socket joint but a collection of articulated bones only held together and aligned by various muscles in the back, chest, arms and chest. If these become weakened or out of balance with each other then all kinds of problems can ensue, tears, inflammation and joint damage. Definitely be worth going to an osteopath or sports injury clinic about this as the exercises involved are not difficult or strenuous and I found it worked to eliminate the problem quite quickly in my case - the only equipment I needed were two 5lb dumbbells and a chart of the exercises. When I started I could not get my elbow up even to shoulder height, now I have full mobility again and no pain.