Hello, Diverticulitis is one of the possible reason of blood in stool. If Your Mother has such symptoms as abdominal pain, fever, nausea and a marked change in bowel habits it may be the reason. Another possibilities includes : -hemorrhoids (the most common symptoms: itching, rectal pain, bleeding during bowel movements) -peptic ulcer (symptoms like: heartburn, nausea or vomiting, burning pain in the stomach between meals or at night) -colon cancer (symptoms like: weakness, change in bowel habits including diarrhea or constipation, blood in stool, abdominal discomfort, feeling that bowel doesn t empty completely, weight loss) -anal fissure (symptoms like pain and bleeding with bowel movements). In my opinion You should make an appointment with Your doctor. Two of the most common tests done when someone has rectal bleeding includes colonoscopy and sigmoidoscopy. It depends on the possible causes of the bleeding. Hope I have answered your query. If you have any further questions I will be happy to help.