I had the same issue with Princess after she was spayed. The vet ruled out a uti & we basically summed it up to the spay and being 'drugged up' afterwards led to accidents, which led to potty regression once she was better from smelling the accidents, etc. We had to start all over with confining, rewarding, etc. though it was much easier than the first time around.
I guarantee Princess has been upset with me, as she has that diva personality, but she's never went potty to 'get back at me'. She will search out a tissue to shred however.
