Check this link to help with crop info. I agree with azygous about possible infection.
https://www.backyardchickens.com/articles/sour-crop-impacted-crop-doughy-crop-prevention-and-treatments-of-crop-disorders.67194/
Place a towel over her nice an snug ( like swaddling a child). this will help you lay her on her back and look closely at each foot leg make note of any swelling, bruising, scaps, and sores ect. If you find anything and can safely take pics that will help us help her. If you do not see anything...