Dead Chicken: Illness?

[MNFowl]

I went out this evening to collect eggs and see if my chickens needed more feed, but I noticed that my one year old Easter Egger was dead. Yesterday she was perfectly fine and as far as I can remember had no symptoms. She was walking normally, eating, drinking, flying, and not coughing or breathing abnormally. The only thing I can see on her is blood around her vent area. I am assuming the other chickens pecked at her, but I am not positive. What illness do you think she had? I want to know if I should medicate my remaining hens. We are getting new chicks on Thursday, and I do not want them to be contaminated. Any ideas would be greatly appreciated.

 

[Wyorp Rock]

Could she possibly have had an egg stuck?