I know next to nothing about chickens, but we recently acquired several. I've never had this problem, but it suddenly seems to be running rampant through my little flock. The chickens will be fine one day, and struggling to breath the next. Some of them are coughing and sneezing. Some get better, but a couple have died. We were using Tetracycline in their water, and there was some general improvement. Now I have another one struggling to breath. Her comb is blueish and her poo is very watery. Any ideas on something else I can try? Could this be why they aren't laying yet? Most of my chickens are six months old by now, but they aren't laying.