It might be good to separate her in the shade in a dog crate with water only. That will keep her out of the feed and allow you to grab her to examine her and have her drink. Massage the crop several times a time downward. Do not massage a soft puffy crop. Most chickens will peck at the chilled...
How does the crop look and feel first thing in the morning. Crops normally fill up gradually as the day goes on while they eat and drink. If it feels full and firm early AM before she eats and drinks, then it may be impacted. Can you get her drinking some water? Some small chunks of cold...