A few days ago I brougt in a stray cat (well, not really a stray. Our downstairs neighbor decided she didn't want her anymore and put her out in the parking lot of our building) Anyhow, I brought her in and our older (14 years old) cat Tonya tore after her immediately. Cutie (the new cat) now stays up on the bed or couch most of the time and won't go down on the floor because of Tonya. The only time she uses her litterbox is if I put her in it and even then it's only a little dribble. Could this be crystals? She doesn't seem to be in any pain or discomfort. She eats a fair amount ( I put her food on the dresser (Tonya can't jump up there) and she eats a fair amount. Any advice?