Cats I have a pretty good knowledge of, unlike chams.
As you’ve already been told, you need to make sure cat doesn’t have any health issues with a vet visit. If cat is healthy, the vet will tell you, “it must be behavioral” and send you on your way. So, you need to then figure out what has changed. Could it be jealous of your cham or another creature, including other humans. Try giving extra love and see if that helps. Is the litter box cleaned regularly? Is it of adequate size and in a convenient but private enough location? Is it an unneutered male? It’s also possible that whoever lived there before you had a cat that left urine odor in that spot. Using enzymatic cleaner and odor neutralizer may only eliminate the odor to our noses. If worse comes to worse, you might try putting a litter box in that spot.
Main thing is that cats do not respond at all to punishment. It only makes them mean and won’t stop the behavior.