I'm assuming you have taken him to the vet and he doesn't have a UTI? You might try some of the sprays they have to keep pets away. I know you can buy them at Petsmart and such. Usually something with a citrus smell will work. Maybe if you crinkle the tinfoil up a little so it's not just flat tinfoil. Maybe it will make more noise or something that he might not like. Can't think of anything else right now, but I'm sure someone else will have more suggestions. Good luck!!!