I have a 5 month old kitten, she has suddenly stopped playing she used to play with her toys, "kill" her toy mouse, hamster, ball etc.She was exceptionally active, running around, being a "normal" kitten. Now ALL she does is sleep, she goes off, shuts herself in her cat carrier and sleeps all day and most of the night. She hasn't been neutered yet, as my vet said they don't neuter until the age of 6 months.