I had necessary surgery for TOS. They found scar tissue wrapped around the thoracic bundle and scalene muscles. I still suffer 2 years later, I have nerve damage from the TOS. I have the same issue of the shoulder hanging being painful. One thing that really helps is having my shoulder taped up twice a week with KT tape. I have treatment from a neurological chiropractor and he tapes my shoulder. It is amazing how much the tape adds support. I have been wearing it for a year now. I probably looks funny, but the comfort I get is worth it.