I recon its your iron. My friend at work use to have that happen when she got up from sitting on parade in high school, cept she would black out and have to sit back down again. She had it bad.
Apparently doctors put u on iron tablets for a while and then after a certain amount of time u go off it for a bit. Cos i don't think its healthy to be on them all the time.
And i agree, having vitamin c while eating meat or having iron tablets helps to take in the iron better
My doc told me that too
I am gunna see the doc on sat and mention this and my lactose prob :p