have you tried garlic water? What food is she currently on?
I would want to try starving the yeast infection. But I'd be worried about starving her in the process.
The treatments Ive heard of, are keeping the hen indoors away from food, including grass etc. Giving her only garlic water, and doing this for 24 hours. This starves the yeast and helps to empty the crop basically. Then they gradually reintroduce food. And start by reintroducing those healthy bacteria cultures back to the bird using yogurt, scrambled egg etc. Small meals, continuing the garlic water. Eventually you would wean her back onto normal foods.
If she's still eating, her crop isnt being able to fully empty, and the yeast has a good environment to keep thriving.
I've never dealt with sour crop, I dont have that experience, I am merely mentioning a method that I've heard great success with. Her situation is somewhat unique, if she's not been eating enough, she'll be weaker and may not handle the fasting period well. So I wouldnt do this just yet, I just want to offer hope that there are other methods on treatment, and I'm sure something will work.
I don't want to give you bad advice in this situation, but I just wanted to throw this information out there. I can find some sources on this in the morning, fron where I found this information.
Her poop is likely watery due to not eating much, and is green due to a combination if not eating, and it is a sign her body is trying to fight an infection. I'm not surprised by her faeces at present.
How tired exactly is she? Is she active in bursts, preening, foraging? Is she still on medications?