Litter box issues
Hello. I first want to say I'm glad I've found an active board of people who may be able to help me.
I have 2 cats, Hikaru and Lost. We have had Hikaru since she was 5 weeks old, and she is around 7 years old. We have had Lost for about a year, and he is between 2-3 years old. First, I should say that Hikaru hated Lost for a long time, so we kept them separated and eased them into each others' company over about 6 months. They did not share a litter box during this time.
Once they got acclimated to each other, they shared a litter box for about 6 months without any problem. We had them sharing one of the large Budda Domes. We had to buy a different type of litter for a short time, and Hikaru peed on the stairs of the box during this time. This is a litter in the past she has used and been fine. But I thought, maybe she's gotten pickier. So we switched litter back, but she still peed on the stairs. She would go in to poop, though.
We ended up getting disposable boxes and putting them in our tiny bathroom. Hikaru claimed them as her own, and never had any issue with them. Having the litter box was just a temporary solution until I could get the Budda Dome super clean AND get a new litter box for her. We recently got the new litter box, but we had to put it next to the well-cleaned Budda Dome.
NOW, Hikaru will use the new box. And she'll go a day (sometimes 2) without any problem, then suddenly, she'll pee on the stairs of the Budda Dome. It's very frustrating, and she knows she isn't supposed to (when we come home, she'll act submissive - which is extremely rare for her), and seems to feel bad when she does it. When I go into the closet where we keep the boxes, she'll put her ears down and squint; something she does when she's in trouble.
I don't know what else to do. It's getting expensive to clean the stairs every day, and it worries me for if we ever have to go on a long trip. We live in a very small apartment and don't have much money, but we do the best we can.
Hopefully someone can help us.
Thanks in advance,