Yogi, hope you feel better. It's probably muscular, and since our backs have HUGE muscles, when they spasm, the pain is just as big as the muscle!

Heat and lay flat if you can. Muscle relaxers would probably help, and so will anti-inflammatories. My doctor told me that sitting is the worst, as it puts all stress on the lower back. He said that standing is actually preferable.

I pulled my back out when I was in my 20s, lifting my daughter the wrong way. It's not old age, just lifting at a bad angle!