My younger brother is Obsessed with eating erasers.

 Ever since He had been in the fourth grade he has been eating erasers(don't ask why). He used to eat erasers a lot and I'm not even sure how he started doing it. It's not as bad anymore, and I thought it would stop. It's been going on for four years, and he just can't stop. He is  extremely serious with it because lately he has eaten more than usual and he can't stop. He always had a compulsion to eat them. He tries to resist as much as possible, but it's no good.  For example, if he erases something on a piece of paper and there are those bits of eraser shavings left over, he will feel the need to eat them or else he will feel mild to severe anxiety.This is extremely embarrassing and it seems extremely stupid, but it's for real. In 5th grade everybody used to know about it because he didn't really care. Looking at him eating those shavings, my sister also started eating them. Now, everybody thinks he have stopped, yet it's getting harder and harder for him to keep it secret from others. and if i tell him to stop he say's please don't say "Just stop eating erasers" because I can't "just stop."