Why does my son 4 year old shakes his head. It happened before bout 4 months ago and now he doing it again. When I first notice it about four months ago he told me his head was hurting. So I took him to the ER to see what's going on doctors said everything was ok so I just forgot about it. It had just stop for no reason. Now he starting it again and he just started kindergarten and I'm more afraid he would be teased or looked at differently.