Two of my chickens started laying a few weeks ago. I got one egg then nothing for two weeks. Then I was getting an egg every few days - then one day I got two eggs. Now for the last 7 days I get shell less eggs. Every day. Sometimes she lays them during the night while they roost. I feed them organic layer feed and they free range in the afternoons until dark. I just put out oyster shells yesterday for them when ever they want. Is there anything else I can do and will this just correct itself?