This article might have some helpful information in it: https://www.backyardchickens.com/articles/how-to-treat-sour-crop-and-impacted-crop-and-how-to-know-which-one-youre-dealing-with.73607/
Gently squeeze it. Is it hard or soft? If soft, was there any sound? Did she puke any? Look it all over. Is there any old or new scabs anywhere on it?
@Wyorp Rock