Question to other members: How do you get the quote thing to work?
meowneko says:
"he still uses his litter box, doesn't mind sharing it with the other four cats except when it's too dirty for HIM, he will poop right in front of it
to "remind" me to clean it NOW"
Are you cleaning the litter box frequently enough? Daily? Don't let your litter tray become dirty, as this could be the source of the smell, not spraying.
It also sounds like he could have a chronic bladder problem. May be a good idea to take him to the vet and get a better expanation of what is wrong with his urinary system.
Why is one of your cats so overweight? Do you feed them all in the same room? Separate the fat one and feed it in a different room. Maybe take him to the vet for dietary advice.
If you're not happy with your vet; go to a different one.
Am I right in understanding that your husband has recently left? This may be causing stress to your cat. But best to get vetinerary advice first.