It's been freezing and snowing where I live. All my 20-24wk old chickens have the bubbly eye, can't breathe, coughing crap. 2 have died. My 4 adults haven't gotten this (they had the same stuff back in the summer). Has the weather brought this on? The babies and adults have been together 2 months +. I have been medicating for 4 days now. Not much improvement. Will I need to disinfect my coop after this and is it safe to add more to my flock this spring. I live in town and don't have very many birds to start with.