Hard knot on the side of his neck!!!!

[Jinxpepper]

Our puppy (Gator(6 lbs)) some how got our 4 week old chick ( Cheepers) out of his box. We found him before he killed Cheepers but now Cheepers has a very hard lump the size of a half dollar on his left breast at the bottom of his neck. When it first happened Cheepers could not stand his left side. But after 3 minutes now Cheepers is eating, drinking, and running around but the lump scares me! Cheepers is my chick I hatched on my lap. He is my baby and we love him so much and DO NOT want to lose him.....