You may have tried these already, but...

In my search, one specialist I was sent to was an opthamologist at a major medical center/teaching hospital who specialized in migraine. I went through a 2 hour evaluation with all kinds of eye tests. Ultimately that was not my cause, but for someone else, with a significant eye component... (?)

http://www.livestrong.com/article/12...aine-symptoms/

Also in my area is a neurologist known by his colleagues as "the headache guy" because his practice is limited solely to headaches/migraine. He DXed me with 3 questions, which blew my mind since I'd been suffering & searching for years. (Treatment was a separate issue -- knowing the cause doesn't necessarily present any guaranteed cures/treatments).

During my multi-year search, I found (as I'm sure you have) innumerable sites that described migraines, their types & causes. Some of the sources surprised me, e.g one was a chiropractic site, another was a nursing site.

http://www.dynamicchiropractic.com/m...&proxyreload=1

(Cannot locate the nursing site)

I hope there may be some clues/ideas here for you.

Doc