My daughter in law is ages 50 and is hospitalized for bloody stool. Her HgB is rapidly decreasing. It went from 88 to 65 in 2 hours. She is not in much pain. No previous symptoms. She does have moderate to severe gastric reflux. A scope was done. No abnormalities were seen. A colonoscopy is planned for the morning. What could be causing this rapid decline in a previously healthy woman with no risk factors except the reflux which was ruled out as a cause.