I have a 22 week old comet that is laying really soft eggshell. The shells are so soft that they break open when she lays them and they are paper thin. She has oyster shells available and is fed very well. What do I do to help these shells harden up. I think the soft shells are causing her problems when she lays them. 2 children, 3 dogs, 2 cats and 21 chickens, with more on the way.