My Chihuahua puppy just had his first shots on 11-22-04 and I have found a small lump between his shoulder blades. Should I be worried or is it from his shots? I feel it move around under his skin. I am not sure where his first shots were administered, but I am worried that he might have a serious problem. Also one of our bigger pups and my chi were playing and the chi got bit. Would that have caused his lump? It is the size of a small marble and not bigger in diameter than a dime. The ball moves under his skin and is hard to the touch...PLEASE HELP!!!!!!!!!!! He is only 8 weeks old born on 09-29-04!