Hope you did get a doctor to look at the liagament (two main ones) tear when it first happened. He's either going to suggest rest (if slight) or a corrective operation, depending on the damage. Usually the injured shoulder and arm are stablelized close to the side, even after a minor tear. Are you sure it's a seperation......
I did go see an orthropedic shortly after I injuried my shoulder, and he told me it was a Grade II or III separation on the AC (acromioclavicular) joint got an x-ray which showed only the separation nothing of the tissue. He did some rotator cuff movements and declared by the range of motion that I should be ok and because of the stability of my shoulder he doesn't think that I torn any of the CC or CA ligaments(coracoclavicular/coracoacromial). Its been 4 months and I just recently went to another doc for 2nd opinion and he wanted to get an MRI to see if there my be any damage to the cuff and maybe even the labrum. Due to insurance reasons I'll have to wait till January for the MRI an go from there...but the pain is still consistent when doing pressing movements and Ive been feeling a lot of strain in the supraspinatus, which is part of the rotator cuff. I think its just compromising for the separation (won't really know until MRI if there are any tears)....So Ive been doing rotator cuff movements with bands and staying light when attempting lateral raises (side,front, rear) any ideas for rehab workouts??