To be on the safe side I would go to the doctor again, and if you can get a cat scan. I had the same pain (except for in the back of my head), and the symptoms were just like you described. It turns out I had a huge arachnoid cyst. I would feel the pain everytime I exercised. So I took 2 weeks off, and now I don't feel it anymore. But for awhile, it was the worst pain I have ever experienced. I couldn't even masturbate without feeling like somone was hitting me with a hammer in the back of the head... Thats when you know its bad.