What is the rectal bleeding a result of if not hemorrhoids?

Depends. Fissures, malignancies, diverticulae are some other conditions that can cause bleeding.
Not just hemorrhoids. Are you sure you have just hemorrhoids? Bleeding from the rectum that recurs may also indicate anal fissures, proctitis (due to infection, inflammatory bowel disease, radiation therapy, stercoral ulcers, rectal prolapse, trauma, etc.) or a bleeding source further upstream. Depending on your age, risk factors, current medication (aspirin, nsaid's, anticoagulants can cause bleeding), get evaluated.