Welcome tfriedman! Has your doctor investigated this? Radiating pain can be a nerve (sciatic) problem or something else. It's best to see a doc so they can order whatever tests you need. Have you fallen recently? If so, it could be anything from a fracture to a injured joint/muscle.
I would tell your doc and see what he/she can do to help you. If you don't have insurance or are underinsured, here's a real good disount plan for those with/without insurance on lab, imaging tests, and presciption drugs. This card even covers pet medications.
Check out the discount card for under/uninsured. Click the previous link and scroll to bottom of page for imaging (x-ray, CT, and MRI scans) and also lab/blood tests. The prices are really good and you don't need a doctor's prescription to have blood tests done. Read about the imaging test discount. I'm not sure if this requires an order, from the doctor, or not; but the other lab/blood tests can be completed without a prescription and the discount is phenomenal!!! The blood tests are approximately 1/3 the retail cost with the FREE card that you print out.
tfriedman, you don't need a doctors order for imaging tests through the above link!!! This program is available through the National Osteoporosis Foundation and it looks fantastic. I haven't used it yet, but will shortly.