Cats usually spend a lot of time grooming themselves. If your cat used to do this but has suddenly changed its grooming habits or even stopped them completely, then you may be worried. Why isn't your cat looking after itself at the moment?
Your Cat Has a Medical Problem
Sometimes, cats stop grooming themselves effectively because they have some kind of health issue. A physical issue may make grooming painful or difficult; a mental problem may make your cat forget to look after itself.