Stomach Pain and Rectal bleeding

My mom was recently diagnosed with Diverticulitis and prescribed antibiotics which may have stopped the bacterial infection but NOT the stomach pain or the rectal bleeding. The bleeding started in February as a clot-like substance after a bowel movement. Now, in June, blood just streams out about a 1/2 cup to 1 cup at a time. I am extremely concerned. She has not received any type of barium x-ray, colonoscopy, sigmoidoscopy, CT scan or anything other than a blood test. I am very concerned that the doctors are not running all possible tests to rule out Crohn's Disease, Diverticular Disease, etc. Why can't a patient's family member demand that certain tests be performed? Everywhere on the internet it says that one experiencing these symptoms should have an abdominal CT scan. The ER doctor today said that it won't show anything with regard to her symptoms. I am at a loss and feel very sad a confused. Please help. Thank you.

[designsbycm]

Go to another doctor!  She MUST have at least a Colonoscopy or a Virtual Colonoscopy to see what is causing the problem.  If it is Diverticulitis, then she should not eat any nuts, seeds, or anything that is small and chunky and can get hung up in her guts.  But, she needs tests BADLY to see what is causing the blood extretion and see exactly what it is.  Take her to another doctor, another hospital, or whatever it takes!