Sounds like what I had, although my pain was in the spinal cord between my shoulder blades. My scapula was pulled way out to the right (right neck dissection with no muscles cut) and I couldn't lift my arm over my head. I spent 9 months in physical therapy getting put back together, although I think if I had gone to the second guy originally, this time would have been more like 4 months.

I suggest you find a good physical therapist. Three of the moves mine used on me that really helped get the shoulder back where it belonged are called 'Trager Technique'. They were 'Glenohumeral Rotation', 'Shoulder Rotational Oscillation' and 'Shoulder Girdle Oscillation'. Once I was strong enough, he then had me on the pulley equipment at the clinic and using a theraband at home. While my arm still won't go up as high as the other one, it is about 98% there. When I had my second neck dissection 4 years later on the left side, I went to PT immediately and had absolutely no loss of range of motion or weaking. PT should be covered by your insurance and is worth evry penny. Get your Dr to recommend a good therapist.

Take care,
Eileen