If your cat is fixed and still spraying it could mean he has a bladder infection. Check your cat food for ash content. The lower the ash content the less likely they will be to get bladder infections. We have bought our cat food for years at costco(dry food) and haven't had a single bladder infection in our cats. We always have four but right now we have 13. In the beginning our cats did that all the time. Once the vet told me why it was happening and what caused it we have never had an infection again and we have rescued cats that came with one but it went away as soon as they started eating the food we have here. Good luck with your problem.