I am reviving this thread because I have exactly the same problem. I have two ten-week-olds, adorable as can be*, and apparently well litter-trained. They’ve been home for five days. The first day and night, I kept them in a very small space, a hallway–because it could be closed off–except when they were with me in the bedroom. First night, one of them peed on the bed. It’s a high bed, and although there were steps, she might not have been able to find them in time. I stripped the bed, cleaned, used baking soda on the spot.
Woke up the next morning, one of them had pooped on the bed, and there was fresh blood mixed with it. Took them to the vet immediately and he couldn’t find anything wrong. I stripped the bed, cleaned, used Nature Clean, and slept on the couch, closing them in their hallway. Next morning (yesterday) I turned the mattress and put a plastic mattress protector on the bed. Fresh sheets and duvet. I also made sure that there were several ways to get up and down and that both kittens could use them. Lots of activity on the bed after lights out: wrestling with each other, pouncing on my toes, climbing up and down. Of course you can guess what’s coming! When I woke up, one of them had pooped on the bed, very messily–no blood this time, happily.
Now, yesterday was my day off, and I spent most of it resting on the bed with one or both of them on and off at various times, and there were no problems. They have also been behaving normally, playing and eating, and their stool has been checked and is free of parasites. They both use the litter box and have had no accidents anywhere else. Is it because it’s dark? That’s really the only difference from the daytime bed rest.
I have a call in to the vet, but any advice from this experienced group would be great!
*purebred Maine Coons, two girls