Greetings. Sorry to hear about the problems you are having with your kitty. I am an ER vet with 16 years of experience and 25 years in the veterinary field. I hope I can help you.
Inappropriate urination can be very frustrating. It can be a behavioral issue which can often be difficult to pinpoint. It is important to make sure there isn't a medical reason for her to be urinating in unusual places.
Common medical causes can include but not limited to
1) Urinary tract infection
2) Urinary crystals or stones
3) Metabolic diseases (Diabetes / Cushings Disease / Hyperthyroidism)
4) Kidney Failure
The first steps to trying to isolate the problem would be (tests can be run step by step)
1) Exam by your veterinarian
2) Urinalysis to evaluate for UTI or crystals or other abnormalities
3) Bloodwork to evaluate for metabolic disease
4) Radiographs to evaluate for bladder stones
5) Ultrasound to evaluate the bladder for masses
If the tests do not show a cause for her symptoms - it may be behavioral and a lot of factors come into play
1) Stress in the household
2) Preference for the type of litter used
3) Number of litter boxes, location of litter boxes
4) Competition with other pets in household
There are anti-anxiety medications that can sometimes help with behavioral issues - but medical causes always need to be ruled out first. An over the counter synthetic hormone diffuser called Feliway can be tried and has shown to help some cats with these type of behavioral issues.
I hope this helped you to understand the possible causes for your cats symptoms and make a decision in you course of further evaluation.
Let me know if you have any other questions and if you feel my answer was helpful - please leave a rating