Dopey, sick hen!! PLEASE HELP ME!

Hi BYCers. I have a hen called Winifred and she has been looking abit sick/dopy. She is normally very graceful and perfect but now she cant even hold her tail up she is so weak and walks around swaying from side to side. I saw her sitting i front of a rotten, cracked egg so i think she may have eaten that. She iis walking around with her beak open but won't drink. I have checked the two other hens but they are fine. Does anyone have any ideas of what to do to? Please respond ASAP!!!!!!!!!!!!!!

THANK YOU BYC