I am a girl, but not a doctor; however, I used to have fainting spells too when I was younger. My doctor also said there was nothing wrong with my blood and it was not debilitating in any way. A little anemic that was made worse by the monthly thing. The whole thing got better as I got older and eventually went away completely.

As rickair said, try to get it treated or at least alleviated. Try a change in diet, exercise, other methods of stress relief.