When son pouts he throws his head backwards and hits the floor- afraid he will damage his head!?

Lately my 13 mo old so has been throwing temper tantrums and when he is sitting on the floor he will throw his head backward and hit the floor- problem is, we have hardwood floors and even on the rugs it is still hard. He still continues to do this time and again. Is this going to cause damage? I can tell it hurts him! What can I do to prevent this?