I am a 26 year old female. I'm 5'1 and 128 lbs. I am stationed at Yokota AFB, Japan. This is the 2nd day that i have been feeling lightheaded. I am very tired throughout the day and take very long naps. I have black stool and horrible gas. I am on Lo-Ovral birth control, protein shakes and I exercise daily. My diet is fairly strict. I eat a lot of vegetables, fruit, whole wheat & grains, fish... I personally have no medical history of any serious illness. Any answers on what could be wrong?.....