I found out what was wrong with my sick chicken. Unfortunately she died. But she caught a chill from an opened window and developed a lung infection. Her lungs filled with fluid and she could not breathe. I spoke with our local chicken expert at the farm store and she recognized the problem right away. She assured me that there was nothing I could have done to help her. All of the other chickens are fine. Thanks for your help. I appreciate all of you so much.