weird cat behavior

My cat, Lucy, has been acting strange lately. She is about 5 years old and has always been a good cat. Recently she has been caught shredding cat food bags, licking grease from a skillet, terrorizing my other cat, and more disturbingly she has been eating from the litter box. Im not sure if it is the actual litter she is eating or what. Is litter harmful to a cat if eaten? Anyone have any suggestions on her recent loss of sanity??

Eating non food items (i.e. cat litter) is called pica. It is often caused by a mineral deficiency. What food are you feeding her? Has she lost any weight?

A vet visit is definitely in order, I would say. When my Trixter was sick from his diabetes (before diagnosis) he was licking grease from skillets and eating like a pig. Please see your vet and figure out what is causing this behaviour.

Definately take her to the vet. My prayers are with your sweet Lucy.