When I first got my chicks I had 8 and in the second week my Buff Orpington chick stopped moving and eating. I seperated her from the rest and tried to get water down her throat with the save a chick in it. She kept opening her mouth like she was trying to breath and seemed unable to. When she tried to get up to move she would fall back down and she was unable to sleep and seemed so exhuasted. this went on for 3 to 4 days. When I picked her up she felt squashy and there was a crackling sound in her abdomen area. I was wondering if she may have had a ruptured yolk sack? Anyway I had to put her down because I hated seeing her suffering so much. The rest of the chicks were fine and have reaching laying age.