One of my 16 month old hens declined extremely rapidly and died just a few hours after displaying symptoms. She came up to me and ate some scratch and then a few minutes later I found her laying in the run breathing through her mouth. I checked for an egg in her vent, but the only symptoms she showed was being unable to stand or walk and breathing rapidly through her mouth. There were a few pieces of scratch in the back of her throat but that's all I could see. Any ideas of what could have happened? She was also in the middle of a molt I think. Should I attempt to perform a necropsy and if so, is there anywhere I can get directions on how to do it? My main concern is seeing if she choked or if she has worms as she was perfectly fine this morning and only minutes before she crashed.