sheila
I was told I had migraines (which I did) however, I discovered by accident that I was addicted to caffeine. Every four hours I would get a violent headache that would make me nauseated and I couldn't bear to open my eyes so I would take Vanquish (not on the market now). It had caffeine in it and perpetuated my problem (unbeknown to me). I was taking so much of this over-the-counter medication that I asked the doctor if I could get addicted to it and he said, no. Caffeine still is a screamer for me. I wonder if it could be something like that for you too. I went through a lot of the same tests you did without finding anything also. What a surprise that it was something so easy. But I suffered for 10 years before I figured it out. Good luck.