Inside cat pooping on floor after UT stone

[Fixie]

Hello everyone, I got to this forum after searching a LOT of times what to do with my kitten. We are from Uruguay (far away, beautiful country).

Anakin is 2 and a half years old, he's a common cat that's always lived inside with us in our apartment (3rd floor). Since day one he's been the best kitten, he did his bussiness in the litterbox with no problem.

Aprox. two months ago, he was having trouble peeing, it turned out to be a UT stone. The vet took it out by hand, with no blood involved and he is peeing beautifuly now after the antibiotics. We switched his food to "Cat Chow" because the other one - we were told by the vet - caused him (and other cats) stones.

The thing is ever since he's been pooping in and out of the box. When we get up and he made on the box, we say "Great, problem solved!!" but then the next morning... We pick up after him everytime, so the litterbox is clean. And we change it all one a week.

Our home is small, so the litter box was in a kitchen's corner from day one and he only did outside about 3 or 4 times before, but now he's moving on to a more transited space: the kitchen passing area. We moved the litterbox to "his spot" and now he has switched to a more centered spot. We can't have the litter in the middle of a 1,2 by 2,2 meters kitchen!! That passing area is the only space we can use to move in the room.

So... we put his litter in the living room, he's peeing real happy (because it had been his secret peeing spot ) but he's pooping in the middle of the kitchen. Is not nice to have a present on the floor each morning but we pick it up and don't yell at him or anything because we learned from Jackson Galaxy is no good.

We are thinking of getting a second litter box but I'm not sure it'll work since it seems he likes the feel of the floor against his cheeks He's our baby and we love him, he's a great companion and we don't want to resent him out of a natural issue.

PS: I've put two drops of bleach because I read they like to pee where they smell bleach, and it helps with pee but not with poo.
PS2: We clean with dish detergent (not dishwasher det. the handwashing liquid one) or with multi-purpose cleaner (Fabuloso)

Could you give me some advice on this? We've run out of ideas