I've seen a few doctors, a general physician, and a psychaitrist and every one of those people tell me that there's nothing physically wrong with me that they can find. All blood tests have been normal, and tests for fatigue causing diseases/viruses have been negative.
I don't think it's a dietary thing, i was only taking the vitamins/supplements because i've heard some people say that it helps them. I eat plenty of fresh fruits and vegetables, get at least 8 hours sleep every night, and try to excercise (within limits) every day.