I have a small flock of Silkies, about 3-4 months old, sexes unknown. I started with 15 and am now down to 12. Chicken #1 died about a month ago. Fine in the morning, that night I found it dead in the coop. Chicken #2 acted a little weak for a couple days during a hot spell (85 degrees, nothing obscenely hot, their run is mostly shaded, the other chickens were acting fine) so I brought it inside to monitor it. Kept it by the AC. Was watching TV when I heard a huge ruckus, went and the chicken was having the worst seizure I have ever seen. Then she went stiff and keeled over dead. This was three days ago. Chicken #3 (my favorite ) was fine yesterday, dead this morning. Again, in the coop instead of in the run. There are no marks on any of these chickens. My coop and run are predator proof, plus I have big dogs that keep everything away, plus I live on an island... there is really nothing out here. None of my chickens are acting weird, sluggish, sneezing, no eye goop. I have brought home ducklings but chicken #1 died before they came home. Also the ducklings are in the house and have had no contact with the chickens (and never will). They are from a reputable hatchery and are the picture of health. I haven't brought home any new birds other than them. I would really appreciate any insight. I am new to chickens, and this is heartbreaking and frustrating, and I feel like a big fat failure. What am I doing wrong? Everyone always has food and water, the coop is clean, the run is spacious.