A colonoscopy and CT scan would be the best tests to evaluate pain the in the lower right quadrant. Things like diverticulitis, colitis, inflammatory bowel disease or colon masses would be ruled out with these tests.
With the pain radiating to the back, you may want to examine the kidneys - with a pelvic CT scan (looking for stones). A kidney ultrasound can also be considered. These options can be discussed with a urologist.
If negative, then irritable bowel syndrome can be considered - and treatment optimized, perhaps with antispasmodic agents.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
Medical Weblog:
kevinmd_b