Hi, I'm new and I've been lurking only for about a week...mea culpa.

I have an 8 year old male cat, who has just gotten over a nasty
cystitis bout (which occurs maybe once a year for him).  Nothing else
has changed except that he now craps behind my desk daily.  I've been
using Nature's Remedy for clean up and that pretty much takes care of
the odor and stain and he'll move 2 feet to the left or the right of
the spot and take a dump there.  He took a dump on my DSL modem
yesterday.  I've taken the Natures Remedy and put it in my carpet
shampooer and spread it over the entire carpet area, yet once it's dry.
He's back.  I used Boundary to keep the cats out of the office
completely, doesn't bother him.

Last night I confined him in my son's bathroom with a bowl of water and
a temporary litter box.  (I have a female cat who would sooner throw
herself in the garbage disposal before relieving herself anywhere but
her litter box).  Yes, our litter box is large, cleaned twice daily and
the room it's in (the Cat's Room) is kept very neat).
I am completely flummoxed. I have to keep him on canned food once a day
due to the supplement we give him to maintain his cystitis situation.
(He's also eating dry food that's for urinary track health).

I rent, so ripping out the carpeting (wall to wall) and replacing it
would not be an option.  I'm sitting in my office now and it stinks
(need to get more Nature's Remedy today to finish the job),

Any thoughts.  I really don't have the facilities to cage this animal
on a regular basis. I enjoy my cats but not at the sacrifice to my
health and well-being and enjoyment of my own home.

Any behavior modifications suggested would be greatly appreciated.

Oh and my vet says he's just acting out because we were shoving meds
down his throat for 2 weeks.  Thanks vet!

Diane