Tim,
a second opinion, even a third can sometimes give answers. There can be a number of different ways to interpret the information that comes from the tests you have taken.

I'm not a human Dr., but as a veterinarian, I can tell you that sometimes even with all the tests, there are just some things we don't know. Its a very frustrating experience. Often, a particular condition is something that Dr.s have never come across. In the veterinary world, we have a network which allows us to post cases where they will be read not only in this country, but others as well. I imagine M.D.s have something similar. There are times when I post a case and not one person can help.

From the patient side of view, I understand your frustration as no Dr.s have been able to tell me why I have constant migraines. There is frustration, some anger, wondering why with all this test information no one can give me an answer. If your Dr. is good, he or she won't be upset or get defensive if you want another opinion.

Sam