I had a baby chick hatch about 24 hours ago and it has a big fluid sack on top of its skull. Has anyone every seen this before? I thought he wouldn't live long but he is up and running around with all the other chicks like nothing is wrong with him. I would appreciate any help as I hate to put him down if he has a chance of living a decent life as he doesn't appear to be in any pain, just a happy go lucky little chick.