Ask the day care people if he does it when he is at school,I still feel this is a learned behavior...
If you are worried that he could really hurt himself taking him to a child psychologist might be a good idea, or have your medical doctor give an opinion or referral.
yes he goes to day care and me and my boyfriend are there watching him and no one does this at home he just does this
Does anyone else do this as it can be a copied behavior,it sounds like he is upset by something, does he go to day care and who looks after him apart from you, does he have plenty of fun and games, reading stories, is his appetite good.?