Have you considered seeing a chiropractor? I went through the same issues with migraines, dizzy spells only to get prescribed drugs that made me more sick when the migraine occured. I took actions into my own hands changing my diet, eating clean, organic and taking supplements for the minerals I was deficient in. Also, you may have classic adrenal fatigue symptoms which is just starting to become more recognized in the medical community, but you would still have to look hard to find someone who is willing to help you treat it, however a chiropractor will help greatly! I agree with Toni that you also have candidia overload (aka yeast) that contributes greatly to adrenal fatigue too.
I live in Chicago, and if you need a good referral to a chiropractor, she is located in the Gold Coast and has a very well-rounded staff, she is not in the business to crack backs, if you need massage therapy or physical therapy she will prescribe that instead, and she has the staff to support such issues.
Another thing to consider is subclinical hypothyroid, a blood test cannot detect this as well. Look up both on google (adrenal fatigue and subclinical hypothyroid). Again, you know your body best...the answer that "this just sometimes happens to you" is not a good enough diagnosis...
Best Wishes,
J. W. MPH
Wellness Educator/Lifestyle and Wellness Consultant