Some advice would be helpful for my cat who keeps going outside of the litter box and on clean laundry/bedding.

Okay so for context I got my cat back in june I believe from a second hand owner and they said he was fine and had no behavior/litter box issues I should know about. But after we left in June for vacation and came back he kept using the bathroom everywhere else but the litter box. We were using pellets before so we switched to actual litter, he used it for a while but today he used the bathroom in a clean basket of laundry. Me and my family are completely devastated because if we can't figure out why he's doing this we'll have to get rid of him. I love him dearly but I can't keep doing the same loads of laundry daily especially where I'm living now since you have to pay to use the washer or dryer. So some advice would be really helpful... Please and thank you..