One of my hens, a jersey giant, who is usually very friendly and active has been acting strange. She went into the coop early yesterday, where she usually is one of the last to leave the barnyard at dusk. She has been there since. She is just kind of sitting around. She usually pecks from my hand very eagerly, and I really haven't seen her eat at all the past 24 hours. I checked her vent, abdomen, and crop...all seem fine. No wheezing, drainage, etc... and when she does walk, she walks fine, but she is mostly just sitting in one spot, closing her eyes. Her combs and wattle are bright fresh red and her eyes are also clear and bright. I'm not sure if she is laying yet, as I have 18 hens, all brown layers, all around 26 weeks old. The rest of the ladies seem perfectly normal. I did change up the feed about 48 hours ago. I went from a fine mash to pellets. Could that have caused a problem? I'm just not sure what to do with her?