Nerve Problem Or Something Else?

In Nov. 2005 I was moving a heavy object from left to right at about chest level. I had a sharp pain that ran from the base of the neck to my left shoulder. At the time it seemed minor but a week later it was so bad, I could barely lift my left arm. I saw an ortho specialist in Jan. 2006 who thought it might be a torn rotator cuff. An ultrasound in Sept 2006 showed no tear. I have also had 3 cortisone shots and 3 prednisone treatments. Being in Canada it can take a long time to get something done (Family doctor has been trying to get an appointment with ortho specialist since Oct 2006). A physiotherapist told me he thinks it might be a nerve problem. I have a constant pain in the back of the neck and shoulder, only get a few hours sleep a night, get bad headaches behind the left eye, sometimes have pain and tingling running down left arm all the way to pinkie finger. Pain increases with any lifting, pulling, and pushing. The left arm feels weak all the time  and often feels like it's going to sleep. I was told I may get to see a specialist in January...maybe, but any advice you can give in the meantime would be greatly appreciated, because even with a specialist's ok it takes about 6 months or more to get an MRI. I am presently on oxazepam and imatriptyline for sleep and pain but it helps very little. Thank you for your time.