What could be causing my shoulder/arm pain?

I was in a car accident 6 years ago. My shoulder/arm pain started shortly after, I have had xrays, ct's, mri's, physical therapy, cortisone shots and have been on pain meds on and off. all the tests show that nothing major is wrong. Doctors have said it was soft tissue damage, bursitis, arthritis, a bone spur and treated with narcotics, antinflamatories, as well as cortisone and lidocaine shots. The pain is still there. I have done 3 rounds of physical therapy and i get some range of motion back but it ends up going right back to it being difficult to even carry a gallon of milk with my arm without pain. I was told today by my doctor that they are thinking i'm getting too dependant on the narcotic pain meds. Sadly these are the only thing that will help the pain subside and let me get on with normal day activities or sleep. I am out of ideas, i feel like all the doctor thinks is that i'm a druggie who is addicted to narcotics. please if you have any ideas of other tests i can do, or what my pain could be please let me know. I'm out of ideas and so down. I am not a addict, i am a person in pain. and I know sometimes withdrawl from narcotics could be muscle and joint pain, but the only thing that hurts is that same arm. Please if anyone can help!!!!