Hi and welcome to HCm.
You should do complete work up and next time it happens go to ER. This sounds like serious intraabdominal pathology. It is important to evaluated intensity of colon
bleeding. At least blood tests shoul have beed sone to see is there sign of anaemia
. Most cause of bleeding are benign but something more serious should be ruled out. This could have been biliary colic
attack too or diverticulitis
,it is hard to say. She should definitely do endoscopic tests and abdominal ulttrasound. Wish you good health.