You need to get her into a crop bra before it gets too far stretched. Once the crop becomes pendulous, it never shrinks back to it's original state. And it's ability to push food out of it becomes impossible. The bird doesn't get enough nutrition, yeasts grow in the crop making the bird sicker.
Here is a great place to get a crop bra. They make these to fit, so it can take several weeks to get them in.
http://crazykfarm.mybigcommerce.com/birdy-bra-crop-supporter-chest-protector/
She is probably shivering because she is not getting enough food going through her. If you are handy with a sewing machine and have some thick material, you might whip one of these bras up yourself. I have used them on slow and sour crops with great success. The constant pressure pushes the food out of the crop at a constant proper rate.
For now, you need to get her warmed up. I would bring her inside for a bit. Have you ever vomited a bird? She might feel incredibly better if you got all or most of that out of her. There is a safe way to do this without aspirating the bird, but you must be careful in doing it.
You are going to hold her like a football in one arm, support her at the crop with the other hand and you are going to lean her forward. This next part is where you MUST do this exactly as I say....once the gunk starts to come out the beak, you must count to
2 only. No longer so they don't aspirate, and then stand her back up. Even
1 second is good. Give her a moment to catch her breath and do it again for only
2 seconds. Chickens can't hold their breath very long, only a second or two. Keep vomiting her until you get as much as you can out. Do this once a day only, and it is best done first thing in the morning when all that gunk is toxic. During the day she needs to absorb food and water. If you are not comfortable doing this, then don't. But it helps them greatly if you can.
Withhold all hard foods like grains, greens, anything the gizzard needs to grind. Water soluble foods only. I like to keep them on damp layer feed only. No sweet things either that might cause more yeast to grow. No free ranging for a while either. I would put probiotics in her water to help replace the good bacteria that has dwindled in her crop. A yeasty crop is a slow crop.
If the crop is not too stretched out, it may return to it's original size in a few weeks to a month.
Start by getting her warmed up for now and vomited if you can. Get her into a crop bra, probitiotics in the water and on a soft foods/water soluble diet. No hard grains or free ranging.
Keep us posted!
