Hi, I Was Diagnosed Anemic Over 15 Years Ago But

Hi,

I was diagnosed anemic over 15 years ago but no doctor has so far been able to identify the cause. The last iron studies, done five months ago, showed that my red blood cells were healthy and the correct size. My doctor immediately put me off my iron supplement, resulting in me being back in his practice two weeks later with a low blood pressure and dizzy spells.
After seeking a second opinion, I was put back on an iron supplement, Autrin, but every month after my cycle the fatigue and dizzy spells return. Should I be taking something stronger? And what could be causing he anemia?

Thank you.