I believe he is getting salts from your skin. Scold him (verbally) when he hurts and praise & pet his ears when he is fine. Most birds like the ears scratched.

He is 8 weeks old and I've had him for two days and he's doing great! He's running around and even falls asleep on me. He loves when I scratch him and doesn't like being in the cage. He just nibbles too hard sometimes, so why does he do it and how can I stop it?