All of a sudden I have three problems (all at the same time): -thin shelled eggs that break in the nesting box -pooping in the nesting box -lots of feather loss These problems all came at the same and right after a below zero cold spell here in the Denver Metro area. I have 3 hens, they have a nice sturdy coop, they free-range the backyard most days. They will be 2 yrs-old on 04/01/17. Last year I did NOT heat the coop. This year during the cold-spell I did put a heat lamp in the coop for a few days and I did NOT let the girls out to roam. They are back to normal routine (no heat at night & roaming the yard all day). Suddenly, last 3 days "POOP in nesting box"! Egg shells so thin they break in the nest. I'm finding lots of feathers on back door mat - where they like to hang out. I don't see any evidence of bugs (mites, etc). I keep the coop pretty clean, but I could do a better job. Work, early darkness, and cold hamper cleaning the coop. HELP!