Can you tell us a little bit about his very early behavior? Was your pregnancy good? Did he eat and sleep well and let you cuddle him? How about his other milestones? On time?
Have you looked into the early childhood program for your son? It is set up to take children who have issues. Also, for diagnostic purposes, which will get him help once he is in school, either take him to a neuropsychologist or go to a teaching hospital that has a comprehensive testing team. His behavior is not the norm. He could have one of many issues and the earlier you find out and get him into interventions, the better the prognosis 
Welcome to the board, but so sorry you have to be here.