Hi,
Welcome to the ehealthforum and I am glad to help you out.
One of the possibilities for your symptoms is of ulcerative colitis which is a type of inflammatory bowel disease (IBD) that affects the lining of the large intestine (colon) and rectum. It can cause abdominal pain, diarrhea and bleeding from the rectum.
Ulcerative colitis (inflammation of the colon) is usually diagnosed by a colonoscopy or barium enema. My suggestion is to consult a physician and get this possibility evaluated.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care.