I've had multiple shoulder injuries... but in reality it's the same problem. Most recently, I rested for 1+months and ended up having pain when I came back. My shoulder blade and muscles had "set" in the wrong position, causing it to irritate my shoulder when I threw. Shoulder blade replacement exercises-mainly done by pinching the shoulder blades and pushing the shoulders down, have once again helped me. I do them multiple times every day. There are specific exercises which you'd need to get from a doctor... if your problem is even close to mine.