6 hens (all different breeds), only 2 are laying so far -- and one's laying "rubber" eggs. They're all 10 months old. Moved them 6 days ago from a 20-bird flock w/ three roosters. Is this typical? (We've put out oyster shell and this morning gave them cottage cheese, which I saw the suspected shell-less egg layer eating.) Previous owner says she only got 4 rubber eggs in 2 years. Is this common with transitioning the flock?