Fatigue after bowel movement?

Ok guys, kinda weird and kinda gross but that’s just how comfortable I am on Fluther! Has anyone else had fatigue after a bowel movement? I’ve looked this up and it’s not uncommon but no one seems to have any answers. Fatigue may be too strong of a word, it’s more like dizziness, weakness, and all you want to do is lie down. (not even sit down.) My energy feels completely drained. I have to recuperate for at least twenty minutes. I’ve tried changed my diet around but nothing seems to help. I’m younger than 20, never been overweight, eat healthy enough. At one point I took vitamins regularly but it didn’t help, just gave me severe mouth ulcers. I have no idea where to go with this. Has anyone had this problem or have any suggestions? Obviously, I have to deal with this everyday and it would be a tremendous help. Thanks!