I had 3 cats and a dog. Shortly after having my first and only child, my male cat started spraying. Cats are funny because things bother them so easily. First, is your cat fixed? Having them fixed is almost always the way to get it to stopped, although the longer you wait, the less likely it will work. Also, have the cat checked for an urinary infection immediately. That can usually be cured right away with medication.
My cat was already fixed, so let me assume yours is too. We went to three different doctors and went through so much before we finally got him to stop. My cat was peeing everywhere. He peed on clothes, our bedding and mattress, random corners, ANYWHERE! It went on for nine months before it stopped as well.
The first doctor put him on some medication (can't remember what) but it did not work. After trying three medications, we still couldn't get anything to work. We went to three doctors and they all told us we had already done everything we could and that we basically had to deal with it. Finally, we went to Bartlett Animal Hospital. They were actually the fourth doctor to tell us we had done everything (including using Feliway) but they called a specialist for us. The specialist prescribed another medication, not well known to most vets, and it worked! He is almost completely off the medicine now... sadly, at the same time putting him on the medicine, we gave him to my parents. He sprayed at their house in the very beginning, but since the med has kicked in, he hasn't done it even once.
If you would like to know the name of the medicine that worked for us, please email me privately because I can't remember what it is called off the top of my head. Also, I recommend bringing him to Bartlett Animal Hospital. I know for a fact they will do more than most other places and they are very familiar with my cats situation and what worked and what didn't (not that that completely matters because every cat is different). Anyway, there are two docs there- Dr. Nelson and Dr. Baker. They both are very good and will know what to do!
Good luck!