I just walked into my coop and found one of my chickens lying on its back dead. Its awful. It was a Red Sex Link- about 16 weeks old. All of my chickens have seemed completely 100% healthy since day 1. My RSL's just started laying about 2 weeks ago. I haven't switched them to layer feed yet since they haven't all started laying so they've been eating grower feed and I've been offering them oyster shells on the side. It doesn't look to be predator related...there's no blood or anything. I haven't done much investigating because I'm not sure what to look for exactly. They live in a huge coop that I try to keep as clean as possible. And I let them free range during the day. I'm going to head out to the coop now to remove the dead chicken. What should I look for? I really need to make sure that this won't happen to the rest of my flock. What should I do? Any suggestions and advice are welcome.