My serama chickens are sick. Nothing has bee n different and up until a few weeks ago I had only had chicks and young birds that I hatched myself. I brought three adult birds in and 4 young birds. One of the young birds exhibited signs of illness shortly after maybe the following morning. It was gasping for air. I just thought it must be hot or something. It wouldn't eat or drink. It died the following morning. Then its sibling got sick. And did the same thing but not as severe. But it also died. I assumed that it was isolated events and that was the end of it. But then one of my original hatchlings got sick I also thought she was sick from something else like genetics or something. Breathing heavy swelling face. she lasted about a week. I started to suspect something else when my ameraucana started gasping a little but it soon went away. So I thought maybe I was hallucinating. But now everyone is sick except the 3 young adults I brought in, my young chicks, and young marans. What has happened?!?! I don't want them to die. I got some tylan 50 and dosed the whole flock last night. But no difference this morning. They have puffy faces, gurgling sounds and some are breathing heavy. I called the state vet and asked if I could send a sample to them. I'm confused at to what happened. The breeder was npip and very reputable so don't believe it was anything from his flock. Maybe the babies got chilled and got some sort of cold? I love my birds so much. They bring me so much joy and they love me as well. They are relying on me to make them better. What else can I do?