So sorry for your loss. If possible can you refrigerate the body, and send it in to your state vet vet this morning? That could get a diagnosis, and help to ease your mind. Tell the state vet that you are a backyard owner, and need to get a necropsy. There are several (six) poultry labs in NC that can do it, and you may be able to drive the body there. @Wyorp Rock may know the closest lab. Here is a link about state vets with contact nimbers, and you can look as well for the closest:
http://www.metzerfarms.com/PoultryLabs.cfm
http://www.metzerfarms.com/PoultryLabs.cfm