Hi I'm new to this and I'm hoping you could help or teach me about chicken respitory problems. I bought 4 chicks in April, raised them, moved them to their coop/run in July and first egg from a black sex link came on labor day. I had 2 black sex links and still have 2 well summers. The 1st black sex link died in October and the 2nd one died on friday. About three months apart. Both were healthy, we're eating their food, along with bugs, little pebbles, sunflower seeds, squash seeds, cracked corn etc. They were social and ran around the backyard whenever I was home. But they would sneeze occasionally. I would hear it once while we were all gardening in the afternoon. I didn't know about vitamins I was supposed to give them. Their eggs were normal, sometimes one of them would lay a double yoked egg, the shells were definitely thicker than store bought eggs. It was usual to me when in October the first chicken to die just sat down and started to pant. Almost as if she could not get enough air. I didn't know what to do, I thought she was over heating or chocking. But there was nothing inside her beak and I really couldn't see that far. She died within 2 hours. Three months later the same thing happened with the second chick. Here is my questions: how do I get vitamins in the other two? Are the other two also destined to die? Does sneezing always end in death? I would say there is plenty off air circulation in the coop. It's raised 3 feet above the ground, w an opening in the bottom for cleaning. It has windows with mesh wire. And I'm not an expert carpenter, there is slight gaps between wood panels. The coop has plenty of direct sun, no mold grows around it. I bought the vitamins and tried covering them in yogurts dropped some in the water but they are fickle I don't know if they are getting enough. Thanks for reading this is cathartic too.