Feeling weak and dizzy but no one can give me any answers

I have been getting so weak and dizzy as well as feeling so nauseated and have migraines/headaches and no one can tell me why. I’ve talked to two doctors with one being my gynecologist about being weak and dizzy and can’t get any answers. In the past week I’ve been to two different hospitals for migraine headaches and haven’t been given a reason as to why I’m suddenly getting them everyday for the last two months. I get so weak that I feel like I’m going to pass out and I have to stop what I’m doing or grab onto something sturdy before I do pass out. None of the doctors want to run test to make sure that nothing is wrong and the hospitals just send me home? What else should I do to try to get answers?