Hello!
I have been through your question.
Related the concern of your girlfriend I need more data like the color of blood ( it is red bright, maroon or black) and amount of
blood in stool. I think this is an emergency and she should meet a gastroenterologist as soon as possible to do a physical examination, see blood pressure, and do a fibrogastroscopy and colonoscopia to find the cause of this hemorrhagia ( to exclude an active ulcer,
colitis,
anal fissure, hemorrhoids, polyps or others intestinal pathologies) , do a full blood count for anemia( to see
RBC and HGB), electrolytes and to start a prompt adequate treatment.
Rectal bleeding is managed first by correcting the low blood volume and anemia if present with blood transfusions and then, determining the site and cause of the bleeding, stopping the bleeding, and preventing future rebleeding.
I hope my answer help you.
I wish your girlfriend a quick recovery.