Bathroom issues

Oscar has 2 litter boxes. One is smaller so that one is outside. He has the a larger one that is inside. He used to use both of them, but now I only see\\hear him using the outside litter box.

I didnt notice this until he got worms, we havent gotten rid of them, but he still isnt using the litter box inside.

I use Tidy Cats litter.

Any ideas or thoughts-

Ashley and Oscar

I take it you want him to use the inside box? I am not sure how you can do that unless you remove the one outside. I do not see any problem as long as Oscar uses A litter box and not your furniture or floors.

Im not sure that he is going to the bathroom enough. He is in the house over night and the inside litter box is never used.