I assume he's neutered; if not, that will help. Also, I've been recommending a prescription drug called Clomicalm that I have 4 of my cats on. No accidents since they started taking it. Very inexpensive, low dosage does the trick, ask your vet about it. As for odor and stain removal, Urine Gone, an enzyme. You can get it at Bed Bath and Beyond or just about anywhere. Follow directions precisely and it works wonders. Good luck. I know how frustrating it can be. I was ready to send mine to the moon!