take him to child specialist dear. he needs medical attention i feel.
I faced similar situation because of my son's behaviour when he was of the same age group. This was around 6 years ago. I had taken him to a pediatrician whose wife was a psychiatrist. They mentioned that at this age, this kind of behavior may crop up and as parents, we have to be strict. If we say no to any demand, it should be firm No even if the child throws tantrum.Take him to nearby park and play area so that he can mingle with other children. Overall, it should be nothing to bother if you keep observing and meet the pediatrician once if you feel it needs doctor's attention.