Help!!!

My baby is 11 months old, almost 1. He’s recently been moving his head back pretty hard. He’ll sometimes just do it out of nowhere or he’ll do it if something is behind his head and hit his head on whatever it is...the wall, his crib, high chair etc. it happens so randomly and it scares me that he’ll hit his head hard. Sometimes he’ll laugh and sometimes he cries after he does it.....anyone else going through this????