It all started when I bought two new chickens and put them in the coop with the rest. Later that day I noticed that one of the new hens was congested and could here gurgling when she would breathe. I gave antibiotic for two weeks when I noticed 2 of my 3 roosters were sneezing and acting lethargic a few days later. neither one has crowed for almost 3 weeks, one started acting better halfway threw the medicine and the other started getting sicker. Now it is the opposite the one rooster that was getting better is starting to sneeze again but the other is still very lethargic. None of my hens got sick just the roosters and only two of the three of them got sick. The one Rooster that never got sick is a Bantnam and does all of the crowing, the two that got sick are: red breasted black phenox and a german spitzhouban(he was pretty fiesty) please help.