I have chickens that lay eggs with no shell. 5 Backyard chickens I just bought them a few weeks old right before winter. They started laying in March. Not to much. Then it seemed like one of the chickens started laying a egg with no shell. Then it slowly spread to what now seems to be all of them. Egg production is one to 2 eggs a day. They all seem very healthy and have nice red combs. Yesterday I got one egg. Today I got two both with rough shells and two with no shells. I have increased their protein and give them extra oyster shells in their food with no results. Please help.