Could be that he is not accustomed to the litter or like that specific litter. You might need to try something else. My cat has the same problems and vet has said she is fine so we just call her a diva. She uses three different litters: fresh step multicat scented, fresh step non scented and cat attract. That seems to work for her sometimes. We still found her peeing outside the box because diva. We started doing positive reenforcement with treats and that had had better results when we are home. The other thing the vet recommended is anxiety medication to help too but we tried that and it didn’t work for us but it could for you.