I have a friend, he gets wild migraines all the time. Dozens and dozens of doctors over 25 years. All he can say at this point is what he thinks doesnt cause them. The issue is diagnosing these sorts of things is tough. You can not exactly crack someone open and poke around and not possibly break things plus the cost of time and money. So you mostly look at the symptoms and hope you can read the tea leaves and get it. For most things that works pretty good. But get a bit out of field of what they do and you will have a bad time with most doctors unless they happen to read the tea leaves correctly. My mother in law went from 'you have the flu' to 'you have stage 4 single cell' in under a week and was dead soon after. She went to the doctor dozens of times about it the months before. We get this idea that doctors are miracle worker wizards. But sometimes you feel like they are playing with bear skins and arrow heads.