Is she able to poop?
A lot of times when a hen has reproductive problems or if there's fluid in the abdomen (Ascites) the crop does not empty very well. Could be that she has a blockage in the gizzard or intestines as well. Most of the time when I've had one that had a lot of fluid in the crop, it was sour too but the hen had repro problems.
I'd treat as Sour, you can try a flush as well too see if that helps move material blocking the gizzard or intestines. Flushes can cause dehydration, so do provide water afterwards, it's possible she may aspirate as well, so keep that in mind.
I'm sorry that she's not improving.
https://www.backyardchickens.com/ar...w-to-know-which-one-youre-dealing-with.73607/