Look up or Google chicken anatomy, and look for the crop. It looks to me like she is adjusting her crop, and that could be an impacted or sour crop. The crop normally empties overnight by early morning, and if it is still full and firm or puffy, she may have a problem. A vet may help or you can try treating yourself. Vomiting her (make sure this is done properly or they can choke to death,) and giving fluids with electrolytes may help. Sometimes antifungal drugs such as nystatin or miconazole are used. Sometimes crop surgery may be needed to clear out a large mass of grasses or hay.
