As I remarked to mrph in Browns on Saturday lunchtime: "There are only so many things you can do with a stretched membrane."
I seem to have fucked my back up again. I wasn't doing anything strenuous or obviously foolish; just straightening out the duvet on the bed. There was a nasty wrenching feeling and then my left leg lost its load-bearing capability.
I'm doing the sensible things: NSAIDs, gentle exercise, a nice hot bath with lavender and melissa oils, and hoping for the best. I'll just have to see how things go.