I just had the same problem!! It started about a week or two ago when orkin came to spray a little. He didnt spray very much, just a spot in a room or two. I just took my kitten to the vets today to see if there was a connection, and they cant find anything wrong with her. She seems to be getting better and better every day about the potty problem. I took the top off the litterbox so they could have more escape routes.
There could be a connection, but at age 18 it’s likely that your cat has a health issue going on. There are tons of things that can lead to improper elimination, but diabetes and renal failure are the most likely candidates in a cat that age. I recommend taking him/her to the vet for a full senior checkup to find out what’s going on. As seniors, their health has a tendency to deteriorate quickly and even the simplest of issues can cause them to fade sooner than one might expect if they’re not caught right away. It’s time for a vet trip… stat.