I know for sure two things: her vomiting is trying to empty it---and you are going to have to induce it manually. second, she is going to need treated with a yeast infection medication. if you do that, she's got a very good chance for recovery, from what I understand.
https://www.backyardchickens.com/t/630307/sour-crop-cured-with-monistat
"Hold her upside down with her head away from you and massage from the bottom to the top of the crop so the liquid is released. After this you can feed her layers pellets mixed with natural yogurt and apple cider vinegar in her water. Repeat this every day until her crop returns to normal, and if it persists for more than a week take her to the vet for anti-fungal medicine. To avoid further problems make sure there is a supply of grit always available. Good luck!" https://www.backyardchickens.com/t/613861/how-to-treat-sour-crop
It should just come pouring out of her. The upsidedown part is important so she doesn't aspirate and breath any of the liquid.
https://www.backyardchickens.com/t/630307/sour-crop-cured-with-monistat
"Hold her upside down with her head away from you and massage from the bottom to the top of the crop so the liquid is released. After this you can feed her layers pellets mixed with natural yogurt and apple cider vinegar in her water. Repeat this every day until her crop returns to normal, and if it persists for more than a week take her to the vet for anti-fungal medicine. To avoid further problems make sure there is a supply of grit always available. Good luck!" https://www.backyardchickens.com/t/613861/how-to-treat-sour-crop
It should just come pouring out of her. The upsidedown part is important so she doesn't aspirate and breath any of the liquid.