It's been over a week and I haven't gotten one useful egg out of the only chicken who is laying. Everyday I find the remains of shell-less eggs that have gone splat on the floor of the hen house. I know that she's not just eating the eggs because I never find any shells, just yolk & membrane! She barely touches the oyster shell I laid out for her and the other ladies. She and the other girls regularly get cheese & yogurt, thanks to my son not eating his lunch at school. They graze my yard for a couple of hours a day. What in the heck is going on?