How is your hen doing? Have you tried offering her yogurt to eat? Or some kind of electrolyte suppliment? It might not work, if she is refusing food, but it might be worth trying.
Hi.
I am not an expert by any means, but I was thinking that it could be an impacted crop. According to ehow, this is the information on it:
Causes
When a chicken is eating too much food at a time, or rough food such as straw or hay that doesn't pass well, the food can get jammed in the...