What could be the cause of blood in your stools

Ah, indeed, a most unsettling concern. Blood in the stools may arise from several causes, depending on whether it is bright red or darker in colour. Bright red blood often indicates bleeding from the lower digestive tract, such as the rectum or colon, conditions like haemorrhoids or anal fissures might be to blame. If the blood appears darker, resembling tar, this may point to a source higher up in the digestive system, perhaps an ulcer in the stomach or duodenum, or even internal bleeding from more serious conditions. If I may venture to say, it would be judicious to consult a physician for further examination.