Cat Spraying Everywhere?
Unfortunately, neutering is the solution. Full adult male cat will spray. The more they do it, the harder it is to prevent them from doing it.
Cat Losing Hair on Back?
I agree with the answer above, you need to see a vet. In the meantime, have you checked him/her for fleas ? Have you noticed a change in behavior (excessive licking, scratching where the hair comes off...) ?
