Headbutting?

My baby, for now, has developed a new disturbing habit. When he gets mad or upset, he headbutts. Originally this was his and daddy's way of saying "hi" (we did this with Thomas too) but it has taken a turn for the worse. No longer is it the cute little ritual it once was. Nor is it a slow soft bump of the foreheads. When Jerry doesn't get his way, you might find him smashing his little head into the wall. Or, in this morning's case, he was trying to smash his head into my leg because I wouldn't pick him up while I was reading my email, and he missed. Yes, my child now has a hole in his head just above his eyebrow (amazingly he hardly bled, but I am sure a nasty bruise is forming). He was aiming for my leg, I think, and hit the corner of the computer keyboard tray instead. Later it was the table, window, and who knows what else is to come. Any suggestions on how to stop this one? I am thinking wrapping his head in pillows might get CPS or DSS called on me....