Why Do I Have Dizziness When I Have A Bowel Movement ?
Painless bleeding per rectum with sometimes passing of fresh blood itself usually occurs with a distal colonic lesion, more so anorectal location, such as anal fissures and hemorrhoids. Such type of blood is more likely to be passed seperate of stool or coating the stool ( never mixed with stool).
Passage of blood without realisation makes it more likely to be secondary to a hemorrhoid. Rarely similar things can happen with a rectal polyp (distal colon).
Dizziness may reflect a large amount of blood loss and a reduced blood volume. Hence I would urge you to go and see your primary at the earliest.
Probably your losing unnoticed blood which can make you anemic, the symptoms of dizzy, lightheadedness can point to anemia.
It can be treated easily if you diagnosed early.
Regards,