Sorry to have been MIA, Twisty. I'll PM you with my email address (if I can remember long enough) so you can hit me directly when this stuff comes up. Yeah, reading the first post I was thinking crystals/blockage/UTI. We make sure to feed a low-ash food so as to minimize the chance for the crystals, but they still happen once in a while. UTI is more common in females, but males can get it too, and the crystals/blockage is more common for males. If your guy is prone to getting them, there is s special (read: more expensive) food you can get from the vet that helps. Two of our guys are on special food for different conditions, and we have to add pumpkin pie filling to a couple of the dishes to help with pooping for a couple of them too. Managing mealtime can be challenging.
Good on you for being aware of his deviation from his usual habits - many people don't pay any attention to that kind of stuff at all.
The peeing around the house can be a real problem if you don't stay on top of it, and you may have to ditch the carpet eventually anyhow. It happened to us in our previoius house, and it's happening to my cousin (39+/- cats) in her house now. They can still smell it even after you clean it up, and they think "Oh! Someone peed here! I better pee on it, to cover up the smell." Not the most effective method, but then cats aren't generally known for their engineering feats.
"Mit der Dummheit kämpfen Götter selbst vergebens."
("Against stupidity, the gods themselves contend in vain.")
-- Friedrich Schiller (1759–1805)
Reality is that which, when you stop believing in it, doesn't go away.
-- Philip K Dick
OK, now let's look at four dimensions on the blackboard.
-- Dr. Joy
English isn't much of a language for swearing. When I studied Ancient Greek I was delighted to discover a single word - Rhaphanidosthai - which translates roughly as "Be thou thrust up the fundament with a radish for adultery."