We have 4 hens and 1 rooster. 2 days ago we noticed the hen's combs were changing colors and decreased laying. No feed changes, always have clean water, plenty of room to forage in our yard, coop cleaned weekly, no known "stressful" incidents recently. 2 of the hens are worse than the others. Our rooster's comb looks normal. We are new to this so any advice or opinions are appreciated!