i went donwn to the chicken house this morning to check for eggs, and there was an egg that had a very thin shell, it had broken. i don't know if someone pecked it, but it wasn't being eaten. i cleaned it up right away though. the chickens have only been laying for a little over a week, and i haven't got them a calcium supply yet. what is the problem? will this hen always lay eggs this way? does she need calcium?