This seems to be an impacted crop and needs immediate treatment as this is a life threatening condition. As a first aid to prevent a circulatory collapse you could give her some sugar water or Coca-Cola.
Here are two methods I use with good results...
Did you feel her crop, is it bloated and squishy or rather like a hard ball? By moving her head and neck this way she is trying to pass whatever might be obstructing her crop.
What does her poop look like, diarrhea?