4 hens - all just turning 2 years old. For the past 6 to 8 weeks the laying has basically stopped. My RR was laying 3 eggs per week and now is down to maybe 1 egg per week. One hen is laying super thin shelled eggs, maybe 1 or 2 per week. End of egg concaves because the shell is so thin. Oyster shell is always available, fresh water, feed. Live in Northern IL so we are seeing signs of Spring. I know one is eating eggs on occasion. Have placed golf balls and a mustard filled egg in the boxes to detour bad behavior. Any ideas what is happening?