Lower back stiffness for several months. X-ray and blood work normal. Bleeding with bowel movement 1 time. Dr. recommends colonoscopy. Other options?

An alternative is. checking your bowel movements for the presence of blood over several months. Colonoscopy is not necessary if tests for blood in the stool are negative over time and there is no family history of colon cancer. Your lower back stiffness is most likely muscular. Try gentle low back exercises every day after a warm shower. See: http://orthoinfo.aaos.org/topic.cfm?topic=a00302.
2 different issues. We're moving away from immediate imaging for back pain w/o red flags (http://www.choosingwisely.org/clinician-lists/american-academy-family-physicians-imaging-low-back-pain/) but after several months, imaging makes sense. MRI might be the next step. Colonoscopy is gold standard to evaluate blood in stool as it allows for both diagnosis & treatment.