Does your arm ever go numb?
Could be a pinched nerve in your neck. I get those on my right arm.
How bad is the pain, and how long have you had it? I def have that sort of pain - it is awful; mine is caused by my messed up neck! I have already had one fusion in the neck and that helped for a while, but now have another herniated disc in my neck, causing the pain from my shoulder all the way down to my finger tips (they also numb up). So it really could be coming from your neck; have you had any MRI's of the area?
I hope you take these answers and do something for yourself because you have every right to be in pain, but you also have the responsibility to seek out the cause and help to ease your pain and hopefully cure your problems!
Best to you.............