Hemorrhoids, an anal fissure, diverticulitis, or (less likely) cancer or a polyp are all possible.
With the history of colon cancer, I would certainly consider an endoscopy to ensure this isn't the case. This can be either a flexible sigmoidoscopy or colonoscopy. It is uncommon, but young adults can have colon cancer as well.
These options can be discussed with your personal physician or in conjunction with a gastroenterologist.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
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