My 11 year old female indoor cat had one eye removed by vet because of infection. Now, 2 months later, eye healed just fine but other problems happening. Her third eyelid covers half of her eye, her mouth is open all the time, she tilts her head back sometimes and stares like in a trance, and drinks a lot of water. She poops, pees, eats, walks normally. She wont clean her face very good and I think that's because her mouth is dry. No drainage from nose or eye. Took her to vet and he couldnt find anything wrong. Any ideas what could be wrong?