I don't in any way want to worry or scare you, but when reading your post I was reminded of a recent "House" episode called "The Jerk", where they suspected some disease that the teen had and tried to stress him out to see if he'd start biting his fingers. He didn't have it, but when you mentioned it, I remembered it. I looked it up and the syndrome is called "Lesch-Nyhan Syndrome" or "Kelley-Seegmiller Syndrome". There's a lot more info on the net for "Lesch-Nyhan". They mentioned this on a page I found describing it... "self-mutilating behaviors – characterized by lip and finger biting – that begin in the second year of life". Here's the link to the page...http://www.ninds.nih.gov/disorders/lesch_nyhan/lesch_nyha.... I am not saying your son has this, just saying I was reminded of it because of the show "House". Please don't let this upset you- just trying to help. Please let me know what happens, okay?