What is causing my neck/head pain?

I have had a horrible pain in my neck and head only on the right side for the last eight weeks. I have taken every kind of pain med otc or prescribed to me including: vicodin, advil, tylenol, flexoril, ultram. I have tried heat, ice and rest. Nothing helps. I had an ultrasound because of a small lump. I have had the lump for years. It was not visualized in the ultrasound. I was prescribed a Medrol dose pack. Which took 95% of the pain away while I was on it. The day I weaned off it the pain returned. I then had a MRI of my cervical spine and my brain. The radiologist report states both were negative. I am at my wits end. The pain is constant, although, it does vary in severity.