Thanks for posting your query here.
You have not mentioned about your age and whether there are any other symptoms apart from blood in stools and pain.
From the description given, I think you need further investigations to find out the cause. Sometimes, there could be bleeding ulcer/inflammation of large bowel and continues to bleed.
Please see Gastroenterologist or Gastric Surgeon. They may have to do camera test - Colonoscopy
to find out the source of bleeding and likely cause.
Please do revert back to us if you have any further query.
Dr Tejas Shah
Critical Care Specialist