I have a 15yr old female, spade kitty, always been very well litter
trained.  She seems to be in good health and everything is outwardly
normal.  But she has started to poop on the carpet a few weeks ago and
she's doing it habitually in the same spot every night.  She STILL pees
in her litter box though, which is the weird part to me.   The litter
box is in the basement which is where she sleeps and hangs out most of
the time so its really no work to get to it.  The spot where she is
pooping is at the opposite end of the basement to her box and its
always in the same spot she's going.  The spot where she goes is also
far away from where she sleeps as well.

What to do???

Thanks!

Paul