Cat Won't Use Litterbox Anymore
This female cat is 17 years old, my GF has had her since birth, and until about 3 months ago, used the litterbox when she needed to (rarely). She is an indoor-outdoor cat, where she spends basically 100% of the time in the hot season outside, and almost 100% of the cold season inside (we let her out in the winter when she wants, and I work from home). Until about 2 weeks ago, she would almost always be in one spot; go outside for a "bathroom" break, go right back to her spot. We also have another cat, and he exclusively uses outdoors as a bathroom unless absolutely necessary.
2.5 years ago, she broke her hip somehow; hit by a car, kicked by someone, fell off a high spot (she has "grand mal" seizures maybe 1-2/year), etc. Doctor reset the bone, we did all the things that needed to be done, and now she's better. However, odd thing we noticed after the injury, is she jumps away from her poop/pee after she's done ... like it's a grenade; she may have done this before, but we don't think so.
Now that it's cold, she's inside all day except for ~5 minute outside breaks (where we are assuming she goes to the bathroom, and definitely licks dirt [prefers clay] ). When it was later fall (lets say November), she was inside long enough that she needed to use the litterbox, so she pooped beside it. So, we cleaned it (it was probably not even used yet), and moved it slightly. Then she peed beside it again; bought a new box, new litter. Then she peed on my clothes (which she sleeps on ALL THE TIME). So, no clothes on the ground anymore, she then peed on a random bag somewhere. Then with immaculate floors, she peed randomly in a hallway. Etc etc, she won't use the litterbox. I also vaguely recall her falling out of our corner litterbox, so maybe she's traumatized.
We took her to the vet, and there's nothing physically wrong with her. We've ensured the litterboxes are immaculate, and spread around the house. So, now she's peeing randomly in the basement, which is "better", but obviously not the best. Positive thing is that she's actually randomly walking around the house like a normal cat, so there's a positive.
Anyone have any advice? I honestly think she WANTS to use a litterbox, as she seems to pick something random to pee on (generally). However, I wonder if she doesn't like how loud it is when she gets in it, is wary of it tipping, etc, and she's been soured to the idea? We use the crystal litter that looks like salt, and no turds are in there for more than maybe 6 hours before I clean it out. I was even debating a "natural" litterbox, full of dirt, but I expect the other cat WOULD use that (he likes digging in plants).