Regarding the UTI - his urine seems very normal and he didn't appear to be in any pain.
However, Watson seemed to become increasingly out of sorts, with a rapid change in behaviour last night. He kept falling out of the hammocks, looked very confused and started cramming his mouth full of litter pellets. When I checked on him just before I had to go to work, he nipped my arm and I think he was head bumping when I touched his head (anyone have a video of that?) Jason said that he was bitey all night, and drew blood from his finger. Poor guy has clearly lost control of his body, as he's spending his time laying flat, peed on himself and is drooling. He doesn't want to be cuddled and gets very upset if I touch his head.
Could this be late-stage PT that he's hidden very well up until this point? There are a lot of similarities to my other two PT rats. But at the same time, it's different - could it be something else, like a stroke?
His littermate, Blooper, also seems under the weather today. I gave him a tiny piece of cookie and he kept dropping it. He didn't want any banana either. He's also fallen off the shelf once or twice which is very unusual for him.