I have an indoor cat, always been indoor since she was born. She will be turning 12 in March. She has started backing up to the corner by our front door and a corner over by where I leave my work bag and backing her butt up and lifting her tail and squirting pee onto the wall, which stinks like all get out.
Anyway she has never done this before and I was wondering what has maybe made her start doing this and why do they do this and what the heck can I do to get her to stop?
She is almost 12 like I said and never was spayed since she has always been an indoor cat.

Any help or advice will be greatly appreciated
Thanks