I'm very sorry to hear about your kitty. I lost a dog in July, and she was not able to keep anything down. I fed her Pedialite to keep her hydrated. She liked the Cherry flavor.
She was leading to get kidney disease also. I had to put her to sleep.
She was 13 years old. The vet said it is from a long time exposure to the chemicals in dog food.
Hope your kitty is better soon.