1. Do your headaches feel like they could be caused by eyestrain at all? Are you on the computer a lot? You could see a neuro ophthalmologist to make sure there isn't a vision problem causing your headaches. A regular ophthalmologist won't be able to diagnose the problem.

2. I would think that it could be even more likely that a neck injury could be contributing to your headaches. I had a personal experience where I thought I was having concussion-related headaches, but really it was a problem with my spine. I had a gap between my C-2 and C-3 vertebrae. Once I went to a physical therapist who was a spine specialist trained in the Mulligan technique, she was able to fix the problem in about a minute. It was amazing. She also taught me how to fix it myself were the problem to recur. I went from having a horrible daily headache for a month and a half, to being pretty much fine. I hope you have an easily fixable problem like this! Whatever is wrong, my advice is, don't stop looking for answers. I also got my vitamin and hormone levels checked, and they were fine, but it could've been something like that contributing to my headaches. You never know! Good luck!