Yes, they usually get impacted(often too much fiber, like long grasses) before they go 'sour'(which is actually a fungal infection).Sour crop
I would search on 'impacted crop'.
But beware the 'vomiting' technique, is high risk of aspiration/drowning.
Isolate her so you can observe her poops.
ETA:
'pendulous crop' is something else to research. A pendulous crop can help cause impaction, or be caused by and after impaction.