Suggest Treatment For Pain And Numbness In Arm

I dislocated my left shoulder watere skiiing 20 years ago. Dislocation hasn't reoccured in about 15 years, but there is a growing pain and nerve problem.Numbness along the back of the arm and pain along with loss of strength. Surgery is out. what are medicine and rehab remedies? Thanks age is 56 weight is 200 height is 6'1" no medical issues with medicine except an allergy to compazine