One of my Hens had black spots on her comb a week ago, then I noticed a couple others. Thought it was just from pecking. Now three of them have pale tips of their combs. Noticed some runny poop out of one of them this morning. All eating, drinking, and still laying, running around like normal. Looked for mites but didnt see any. It did get pretty cold a few nights ago, like 10 degrees Fahrenheit overnight. Any advice?