my son is a nail bitter too, and he is now 5, i wish he too, would stop, but it seems like when he is nervous, that then is when he chews.... let me know if anyone finds a solution:)
I wish I could help. My son started chewing his fingernails when he was 2 and he's 3 now. He's not making them bleed at least, so I haven't done too much. I was hoping he'd outgrow this.
If anybody else has any suggestions, I'd be interested too.