He's funny when he drinks - he paws the floor to the left of the water bowl, as if he's bringing the stuff up out of the ground. Must be a habit he picked up as a baby on the streets, pawing at stuff in the gutter to get to water underneath. He doesn't do this at the food bowl. He even kept doing it after I replaced the stationary water bowl with one of those water pump thingies.
He raced me up the stairs, no wobble, no hesitation. Jumped up on the bed easily. Looks like his old self is back.
I called the vet's and gave them the good news. They're open late on Thursdays, and I talked to a live human.