Bleeding in the anus, bowel or lower gut from injury or another problem blood in poo, change in pooing habits (like looser poo, diarrhoea or constipation ), slime with poo bowel polyps ,. Hemorrhoids are swollen veins in the rectum or anus, and cause pain, itching, bleeding, and irritation. An anal fissure, a tear in the anal tissue, causes pain and bleeding, especially during bowel movements. Campylobacter is an intestinal infection causing abdominal pain and cramping, nausea, diarrhea, and vomiting. Rectal bleeding after bowel movement is a sign that your digestion is problematic, which could be one of the deep hemorrhoid traits. This condition is caused by increased pressure on the veins around the rectum and anus. At your age , usually hemorrhoid bleed especially if it is on the tp! If you r constipated( round or hard stools or straining when you go , not how often) you can get hemorrhoids or small cuts in the skin of the area called a fissure that can bleed too. The bleeding may result in bright red blood in the stool as well as maroon colored or black stool. The bleeding also may be occult (not visible with the human eye). The common causes of rectal bleeding from the colon include anal fissure, hemorrhoids, diverticulosis, colon cancer and polyps, colonic polyp removal, angiodysplasias. An anal fissure is a small cut or tear in the lining of the anus. The crack in the skin causes severe pain and some bright red bleeding during and after bowel movements. an anal fissure may develop when you pass hard or large stools during a bowel movement. Anal fissures typically cause pain and bleeding with bowel movements. When an anal fissure occurs, the tear can expose the ring of muscle that holds your anus closed. An anal fissure is a small tear in the skin at the opening of the rectum. It is usually caused as a result of straining and stretching the rectum when passing a hard stool. Anal fissures can also occur if the anal sphincter (the muscle that controls the anal opening) is too tight to pass stools.