I had to spend the day in bed, of course, as I was working last night, and so I didn't notice that anything was wrong until the late afternoon. He had spent all night and all day in the house AFAIK, as it's been raining heavily, and I actually wondered if he'd strained something by holding himself in for many hours. He's very good about not going in the house - he won't even use a litter tray, alas - but he hates going out in the rain.
I was on the verge of calling the vet when he came racing through the house, made a flying leap to the top of the table where the broadband router stands, and curled up on it (his favourite spot) and I thought "whatever it was must be okay now". Only, once the vet was closed and it was too late to take him, it turned out that he is still limping heavily. It does seem to be one of his front paws that can't properly weight-bear, so the toilet-related hypothesis is probably disproved, but I can't find any sign of injury. He's moving very oddly, however, and I'm baffled and worried.
CW and K are still away. I've got to go out to work and leave him all on his own all night again. I hate leaving him, but there's nothing that I can do to avoid it. Even when I come home I'm going to have to go to bed; I've got to go and pick CW and daughter up from the ferry tomorrow tea-time, and if I try staying up all day I won't be able to drive safely. Maybe I'll be able to get him to come to bed with me.
This has rather put a damper on my plan to get some work done on "Sunnydale Passions" today; hopefully I'll be able to do some tomorrow.