Cat not always using litter box
Okay, I'll try to get all the information I can so you won't need to ask for more. I have two cats. Koopa is over 2 years old female, and Poe is over 1 year old male. I have had Koopa for 2 years, and Poe for 1. They get along for the most part, but Poe does try to dominate Koopa often, like nipping at her when they run ahead of me when I'm about to feed them. Anyway, I doubt that matters. So, Poe has off and on pooped outside the litter box, since a few months since getting him. He would do it right outside, even if the litter box was freshly scooped or fresh litter. I switched the litter around, and he still did it. For awhile, he pooped and peed on my boyfriend's clothes that were on the floor, but I got him to stop with a No Spray bottle, which I would spray over his clothes. A combination of that, and finally getting the clothes picked up ended that. A few months ago, he pooped and peed all over some papers that were on the floor near his litter box. He even pooped and peed RIGHT NEXT to his food/water bowl, which I thought was very strange. Once again, we cleaned up all the stuff he was doing his business on, and he stopped.
Now, Koopa had some problem with peeing in weird places, so I took her to vet and they said she had crystals in her urine, and now both her and Poe are on special food, bought from the vet, to get rid of those crystals. I asked the vet about Poe's behavior, and she suggested another litter box, and removing the hood that was on the current litter box we had. I did both of these. Now he has two litter boxes to choose from, both without hoods or pan liners. (They didn't seem to care for the liners, as they tore them up). We kept the second litter box in our bathroom. Alas, someone (I couldn't ever find out which cat) started peeing all over the floor in the bathroom between the litter box and the toilet. Poe (I caught him), was pooping outside the box. I put a towel under the box to keep the stray litter from getting everywhere, and he pooped all over it, so I removed it. By now, I'm convinced he just likes to poop on cloth if possible. So I keep the towels off the floor. Then, he pulled towels onto the floor and pooped on them.
Frustrated, I moved the litter box into the laundry room, and changed the litter. Ahh, they seem to like this litter, and the peeing in our bathroom stopped. Alas, Poe still poops outside the box, and in our bathroom. He grabbed another towel and pooped on that and on our bath mat. I moved the towel he pooped on into the corner while I was cleaning the poop up. Poe walks in and starts to pee on that same towel! I wash both mat and towel. I'm going to relocate our towels to hopefully a cat-free zone.
So, I think that's all the information I have, but if you need more let me know. Poe continually poops outside his box, despite a new box, different litter, fresh litter, freshly scooped out box, better food, and better location. I am really fed up with finding poop outside the box, and on my towels. I really need help, does anyone have any advice? The only thing I can think of is to take him to vet, but I just, don't have the money for an expensive visit + lab fees and whatever else will be tacked on, especially after I did that with Koopa for her crystals.
Any advice would be more than welcome. Thank you very much.