European Burmese kittens & cats in Gulfport, Mississippi

Kahner was born August 7, 2023. We brought him home Nov 2023 and he has lived with 4 other cats. He ended up with a tapeworm in Dec 2025 (we have a screened in pool area that the cats are allowed to access during the day). He evidently ate something that caused the tapeworm. He was treated and had "clean bloodwork" after treatment. We also had follow-up bloodwork and fecal testing done which also came back clean. However, since the tapeworm incident he had stopped urinating in the litter boxes we have in the house. I have a camera set up near the litter boxes and there are days he will urinate in the litter boxes but then other days he will not. We have also tried "kitty Prozac" for several months which did not make a difference. He gets along fine with the other 4 cats we have in the house, he is very sweet and cuddly with us. At this point I just don't know what to do for him. We love him dearly but I don't know if being in a "single animal" household is what he needs.