How to stop him from banging his head?

My son is almost 2 years old (in a few months) and hes got some peculiar behaviors. He throws tantrums frequently where he throws his entire body on the floor head first. Lately in addition to tantrums hes been randomly banging his head on things, for example he will bend down and bang his head on the coffee table- on purpose. Today I caught him trying to bang his head on his bedroom window! I know its not normal behavior and I’m looking into it but in the meantime I’m concerned for his safety especially when I’m not around during the days. Aside from a helmet which he would not wear anyway how can I help him to stop banging his head or protect him better from injury?