What Causes Painful Bump On The Back Of Neck?

A few years ago I notice a lump on the back (right side) of my neck, by the hairline, and even with my ear. About a year ago I went to my doctor who had me do an MRI and Xray. Found out I had degenerating disc and sent me to get shots in my neck. Those did not work and only made it worse. Got a second opinion who decided to try physical therapy first. That worked well for about two weeks. Then the bump came back causing me a migraine for three days. Went back to the doctor who decided to do another MRI. He could not figure out why my pain was all on the right side when it should have been on the left. So, he decided to do an ACDF of c3 and c4. The lump decided to mellow out for a bit and came back causing me pain again. Doing my physical therapy now and they think its a muscle. Again, it mellows out for awhile and back again causing me pain. Its solid and a hard lump. If you rub on it to much it will cause a headache or like a shock through my head. I wake up sore and in pain every day. The pain goes down my arm and into my hand, that makes it hard to open things with my right hand. Nothing is helping and not sure what to do next. See my doctor on the 23rd of March for an xray of my surgery. What should I have them do next or what is this lump that causes me so much pain and will NOT go away.