Our 2 1/2 year old hen became listless a few days ago and started "throwing up" reddish goop. She wouldn't get up. My kids placed her in the coop and when we came back 2 hours later, she was dead. It was all so sudden. She seemed totally fine the day before. Any idea what killed her? There were lots of mushrooms in my yard, and one of them appeared to be torn into pieces. We thought maybe the mushroom was poisonous. We have 8 other hens and they are all fine.