Head Banging

So while I was gone, Grant developed a new form of tantrum- banging his head on the floor. When we came home from the airport yesterday, Grant wanted to watch tv instead of eat dinner. When I told him he couldn't watch tv right then, he got down on his hands and knees and started banging his head on the floor. I was shocked and immediately made him stop. A little while later he was playing with his kitchen and something must have made him mad because he first hit himself in the head, then got down to bang his head on the (hard)wood floor (just once), and then moved to the rug and started banging away again. At least he had the sense to move to the rug instead of the hard floor (I have to admit, it was just a little tiny bit funny). But seriously, where is this coming from? I ignored him the second time he did it, but it's so hard. It can't feel very good! I hope this is short lived...