The cat suddenly becomes very afraid of people and refuses to be touched. It may be caused by the cat reaching estrus, being sick, or being stimulated by the outside world. First, you must confirm whether the cat has reached estrus or is frightened. If so, there is no need to worry. It will subside in a few days. If not, it is best to take the cat to the pet hospital for a check-up to see if the pain is caused by the cat being sick.