This reminds me of a third option that I'm surprised I didn't think of earlier: the Alexander Technique. Tension arising in the neck and upper back areas is practically their specialty. I got some amazing results working with a good Alexander teacher.

Incidentally, if your situation is anything like mine (and of course I don't know), you may need to make some changes in your life in order for the pain to go away. I'm not talking about techniques, I mean fundamental personal change. I had a headache for 9 years. No one ever explained it. But it eventually went away as I addressed some important issues in my life.