How frightening for you. Is there any chance she ate something she shouldn't have? Often after several bouts of diaherria there will be blood in it. If its bright red its probably caused by irritation from the diaherria . But I am worried she could be trying to pass something. I would go to my regular vet and request X-rays. Sadly, not all obstructions will show up on X-rays tho. You can give her the bland diet.. No kibble at all. Just rice, boiled chicken ..look up bland diet here. There are lots if threads. I sooo hope she is ok... But if it were me..tomorrow she goes for a thorough going over.