I have a pain problem...

I have this pain in my upper back kinda in my shoulder. I've had it for a long time now. I've had X-ray's taken of my back and shoulder, and they can't find anthing. The pain is sharp some of the time. When you touch my back I feel somewhat of numbness, but I can still tell you touch me. Some days are worse than others. I can go a while with no pain and then it'll hit me as soon as I move the wrong way. I can't take it anymore. I'm going to lose it. This is by far the most annoying thing that has ever happened to me. I've took medicine for pain but nothing I've taken has helped. What is wrong? Can anyone heelp me. Please, I am desperate.