SodaPop is in the hospital tonight.
He'd been off his food for a couple of days, and yesterday evening and last night all he wanted to do was sleep and sleep and sleep. When he was still lethargic when I got home from work tonight, and still not eating, I called the vet.
She said to bring him right in. It turns out he had a temp of 105, which I guess is quite high for a cat.
The vet seems confident that this is just a one-off, that he picked up a bug somehow (because God knows he's been vaccinated for everything known to man), and with an overnight stay and some IV fluids and something to bring the temp down, he will be fine.
It just seems awful quiet around here ... get well soon, SodaPop!