Last first....no it has to be biological.
I would make a guess that at moment she is just sitting anywhere to try and go,,,,,,,,,,,,,,,,,,however stress can cause cystitus!
I knew Misa had it when he was in and out of trays when he usually goes outside and also new it was caused by stress cos Franta was getting loads of attention cos he had just started having seizures and Misa is such a sensitive soul.
Abs worked for Misa and do hope that Katie improves quickly, I would leave her at the moment.....has anything new happened to make her feel stressed?