I second what Nancy said--bring the cat to the vet along with a urine sample if you can (otherwise, they can extract one there). You need to rule out a medical issue first.
When you say de-scent spray, are you referring to an enzymatic cleaner? You will need to apply this liberally on the couch and any other item that was peed on. Just spraying a little on won't work; the item(s) need to be saturated for the product to remove the odor completely.
Can you limit the cat's access to the room until you fix the problem? Also, do not leave anything that's attractive to him lying around, like laundry, rugs, etc.
Please let us know how things are going and I can offer more suggestions based on what the vet says.
Happiness is being kneaded.
Avatar is my childhood kitty, Berries.