DH has been having head trouble for over a month...

Ok so we've gone to the doctors about 5-6 times and the ER about 3 times... they all say there's nothing they can find. they've done blood tests, CTscans, ultrasounds. nothing has come up of y he feels this way.... He gets light headed alot and nearly collapses, gets fatigued easily, feels weak, and says he feels pressure in his forehead. I feel like it could be that he's not getting the nutrition he needs. I tell him to try taking vitamins (we are having problems getting enough healthy food to last) and he refuses to. I tell him that everything he is feeling is how I feel if I skip on my prenatal or don't eat correctly. We also found out he has acid reflux... I don't know what to do in worried... Please any advice is welcome....