during the winter I lost several chickens to some kind of respiratory illness. These chickens as well as the rest of my flock shared a 10x10 coop. I have since gotten a larger coop and use this smaller one as a grow off coop for my babies. Right now, I have my 10 week old babies in the coop (approx 25) They are starting to get sick. Not the respiratory stuff--but drooping wings, puffing out their feathers a bit, shoulders appear to be up--or their heads are set down into their shoulders...however you want to say it...they seem depressed and sit off alone and eventually die. I lost 3 yesterday and 1 today. I found one dead last week buried under the shavings--but never noticed that it was sick or getting sick. They have the coop to themselves; so they aren't sharing it with any of the big chickens. What is wrong with them? is there something in the coop like a parasite? If I clean that coop out...remove all shaving, clean out all nesting boxes etc...how feasible is it to "really clean " it?. I mean, it is a wood floor. It isn't feasible to wash it down with a bleach water solution and really clean it. The roost and the top of the nesting boxes are covered with dried poop. I scrap it off with a shovel--but it will never b "clean"... But I don't know what else to do--is there some kinda of spray that I could use ? What is causing these babies to die?