Hi. I'm Dr. Gotthelf. I have been a vet for 35 years and I would like to use my experience to help you with your pet's medical problem.
This could be a behavioral problem rather than a medical problem. I have found that when cats are peeing on objects, they are not happy. I will often try a human antidepressant that works well in most cats to make them feel better psychologically. It is called Elavil. Ask your vet if your cat could try some for 2 weeks to see if that makes a difference. It really has no side effects.