For three years I had pain in 5th lumbar so bad that I couldn't function much less excercise. I slept in a recliner and never had a day without pain. Some days it was so bad I couldn't move at all.
Diagnosis after x-rays - osteoarthritis with hardly any disk left in the 5th. Prescribed Vioxx which I did't take because of the indicators of heart which my family has history with.
So back to square one which sent me on the internet and the spinal health web site.
One excercise....JUST ONE...has made me pain free ever since.
A stretch that involves lower back, down thru the hamstrings.

After you have gotten better with maybe ice (helped me best usually) and or heat later, try laying on the floor with you legs slightly bent and up. Drape a towel over the bottom of your feet and gently pull your legs with it toward you torso. Only as far as comfortable and hold this stretch for 30 to 90 seconds. Repeat as it feels good and do this daily for a few. It occured to me that my hamstrings were too tight from all the walking and excercising I did, that it effected my lower lumbar in the worst possible way.
I now have been pain free (for the most part) for 2 years. I have to watch how I move in bending etc. but I work out with weights, do abs and back extensions and they don't bother me at all. I even lift pop bottle cases etc.
I am telling everyone I know with lower back pain, and I have gotten nothing but positive feedback thru this stretch.
Its unbelievable that all the practors and docs had rather given me a drug which we now know isn't even safe.

Try it, but also see a doc to get a diagnosis first, so you know what you may be dealing with.
hope it helps