Cat pooing in house suddenly - WHY?? And tips to stop???

[Hadeda]

title says it all really.
Friday morning on DD2's duvet
Saturday morning on DD1's duvet
Sunday was meowling around so I opened the door and shoo-ed her out, no poo
Monday some time - on DD1's duvet again!
Tuesday early morning - at the bottom of the stairs and I stood in it!!!!! Yuk yuk yuk

She is about 12, we have her and her brother. The poos are quite normal looking, no blood or funny stuff. Her bum looks normal too, no redness or swelling. The cat flap is working fine, I've tested it and Harry is going in and out normally. And Molly is weeing outside fine, just poos inside.
Only real difference is that DH and the DDs are away at present, left on Tuesday night to visit grandparents. But I'm still home so it's not like she's been left with a sitter and is holding a dirty protest.

So what is going on???? And how can I stop it????
Think I'll have to take her to the vet to be sure all ok, but my instinct says she needs a shrink not a vet.

Any ideas all cat experts here? Cleaning up poo every day is very tedious....

hi there. iam a qulified and listed veterinay nurse with cat behaviour qulifications. i can completly understand your frustration.
cats can begin to deposit urine and/of feaces around the home for many difference reasons. mainly marking behviours or simple that they have devloped an aversion to the itter box. its never a protest towards you as cats dont posees them thought processes. given your cats age a vet check is an absoulte must to check for any early signs of a medical complint. artritis can be a big issue with our older cats just simpling makin it difficult to use the tray, some cats candevlop a dislike with the litter tray if they assciate it with pain ( ie squatting to defeacte) does your cat eva weee around the house or does she always go out side for this? have u recently changed litter tray type of litter type? have you changed to position of the litter tray? forgive the spelling, i type too fast,

Thank you!! That's really helpful.

The cats don't use a litter tray, they go in the garden. It has been cold so perhaps she is either finding the ground too hard to dig or just doesn't want to go in the cold. She is going outside to wee, just the poos are inside.

I'll ring the vet and see if they have an early appointment tomorrow. But thank you for your really quick and knowledgeable response!!!

its good that your taking her to see your vet, allowing her a alternative more approipate place inside would be a good idea, i would get her alitter box to use inside.