I had another thought about her not using the litter box. What kind of litter do you use? She may not like the feel of the litter on her poor little toes. I know my cats do less digging for pee than for poop. In fact, I have two or three who will hop into the litter box, pee on top of the litter, and hop out, all without so much as scratching at the litter. They are much more vigorous digging a hole for the poop and covering it up.