One of my cats has been urinating everywhere but her litter box. She and her sister share the same litter box and my husband changes it frequently. Are we not changing it enough? They are nearly 4 years old and this has just recently become a problem. She did also deficate on the rug in the bathroom but that is only the 2nd time this has happened. What can we do to get her to stop this and what is your recommendation on a product that REALLY works on furniture that is fabric. She urinated on a sheet and it was on the couch and soaked through. Thank you!