I have a 1.5 year old buff orpington that has been laying only thin-shelled eggs for going on 2 months. The other hens' eggs are normal with nice thick shells. I switched from all flock to laying feed when I first noticed the problem, and they also get crushed oyster shell and I see my problem chicken eating both the feed and the free-choice oyster shells. They get veggie snacks as well as mealworms occasionally. Is there anything else I could be doing to increase her egg quality or should I consider culling her early if this keeps up?