Lewis,
I don't have back problems ... knocking on wood ... but, a couple of times over the past 15 years or so, I have been down for the count for a day or two due to a muscle strain in my lower back. It happens. And suffering from an excruciating pain in one's lower back has a very annoying tendency to put you out of commission for as long as it lasts. Funny thing is ... whenever one of those muscle strains in my lower back incapacitated me, I did NOT remember ANYTHING that could have caused the muscle to tear in the first place! Isn't growing old wonderful?
B.

The essential American soul is hard, isolate, stoic, and a killer. It has never yet melted. ~ D.H. Lawrence