recently i purchased some buff orpingtons from a local sale. one hen was sick and has been kept in her own cage. the rest of the opringtons were isolated as well.. until one chicken decided they could jump to the rafters.. hop along the beams and get into my main flock.. and now all the young chickens, they are about three months old (australorps) are all sneezing and shaking there heads like they have runny noses. I have been googling for hours and I cant get ahead on this one.. the beaks I smelled of the sick ones smell like chicken poop. not rotting or puss.. just poopy where as the non sick ones smell like well. warm chicken lol.. I don't know if this sounds like a viral infection or what.. I culled that hen tonight as she was not getting better. it seems like its just the chicks.. the older birds.. six+ months all seem fine.. except one turkey.. I have started adding apple cider vinegar to their water and I uped the corn ration to heat up their food. they are still eating and drinking normally. no diarrhea.. no loss in egg production from the older birds. I ALSO DELOUSED THEM ABOUT A WEEK AND A HALF AGO.. I don't know if the powder being there could have caused them a bit of trouble? please help I need suggestions. should I antibiotic? what do you guys recommend? I saw one thread that recommended culling the whole flock but I have sixty some chickens and they just started laying!!!