What Is The Cause And Treatment For Shoulder Pain?

I have been having shoulder pain for the past 6 months now. the doctor said it was tendonitis. it hurts so much and I cant sleep. he gave my 20 tramadol 50mg pills 2 months ago. they help me sleep but he doesn t want to prescribe anymore for me. I also have arthritis on my fingers on both hands. what do I need to do to get some medication for pain?