My cat has started crapping outside her litter box around the house. This started about 4 months ago. My other cat does her deeds in the litter still. I've tried everything I can think of.

Took her to the vet and had her checked, specifically for a bladder infection or UTI.
Added a litter box with attractive litter and make sure the litters are always clean.
Put plug-in deterrents around the house.

Please, someone with a crappy cat tell me how to fix this. My husband is about ready to get rid of her.