So about 1 week ago I added an 11 day old chick to my 5 day old chicks. The 11 day old came from my dad--it was the only chick he incubated survive. Yesterday we had to put him down. He was perfectly fine until yesterday morning we woke up to him stumbling all over his box and the other chicks wouldn't go near him. He was not injured that would could see. Then my husband found him laying on his back unable to get up a couple hours later and breathing very heavily. He wouldn't open his eyes or anything. He never really liked being picked up and would just fight--well, he didn't even try to resist when my husband picked him up. We had seperated him in the morning and as the day went on his breathing became worse and he continued to not move-he hadn't moved in hours--so my husband put him down since he was only suffering. All of my other chicks seemed perfectly fine until tonight. I checked on them before bedtime and one of my americaunas (was a 5 day old) was laying in the box breathing heavily, won't walk, and the others were all at the other end of the box seemingly feeling just fine. He had some yellowish runny poop outside of his butt so i thought maybe he was clogged up--but he wasn't, it was just runny. We have not changed anything with them--food or anything. There brooder box is kept very clean, water and food too. I am at a loss and have no idea what could be going on. We separated him from the other chicks for the night and will see how he's doing in the morning. If anybody has any idea what could be wrong and if my other chicks are in danger--please let me know. Thanks so much!