I've got a 3 week old light brahma chick who has a bump on his head. I first noticed it about 1 1/2 weeks ago, but didn't think much of it. But it's not going away. It actually looks like a pimple...or a small blister. The chick is normal in all other aspects...eating, drinking, pooping, playing, etc. What could this be, and should I consider culling it? Below is a pic, though not the greatest. I've searched the internet trying to figure out what it could be, but can't find anything about chicken pimples.