As someone who has badly damanged both shoulders (dislocations mostly, and twice what they called a severe sprain of my right), do what the doctor tells you!!! Believe it or not, they actually know what they're talking about!! If I'd listened, I wouldn't be in so much pain, and I wouldn't be so close to disability at the tender age of 32. I have arthritis in both shoulders, I can't lift anything over 10-15 pounds without a lot of pain, I have very limited mobility in both shoulders, and I'm looking at replacement surgery of my right one in the near future. I know its frustrating, but keep it immobilized as much as possible. Slight movement to relieve cramped muscles shouldn't do much damage, but you should ask the doc about it to be on the safe side. They should be getting you into some physical therapy soon so that you don't get frozen shoulder (complete loss of mobility). Best of luck!! I hope you heal up quickly. Take care of yourself!!