Poorly furry baby

This is Buster. He’s 9 but you’d never know it to look at or watch him. Lots of character. Cheeky. Playful. Talks to me. Answers when I speak to him. Constantly demands food. Wednesday morning found crouched on his scratch pad, face up to the wall. Oh boy.....in to veterinary hospital. Kept in two nights. The gentlest cat you could ever meet.....well, not according to the vet. Refused to eat so knew something was pretty wrong. No tumours. Bladder stones though. Attacked all the veterinary staff. Came home and just wanted cuddles from dad