Thank you everyone.
@TwoCrows, your reply made me realize something: Rusty won't vomit up a big liquidy mass because it's not there! Her crop is full of air, not liquid and food! Last week, when the infection was high, I think there was liquid in the crop top. But now it looks like liquids are moving down but this gassy air is getting stuck.
(In the other cases of sour crop I've dealt with, it was liquid in the crop, so this is new to me)
After I posted last night, Rusty was better, so I spent a few minutes gently massaging the crop in a different way. Usually with a sour crop I try to direct the contents of the crop toward the crop drain. But with Rusty, I did more of a "burping" motion --gently massaging upward towards her beak. I could actually hear the gas hissing out from her nostrils, and then she made a huge burp, opening her beak to push more gassy air out. It's when she does this that it's scary because gas is getting out, but she's not getting oxygen in.
I have Celiac's so before I figured out how to adjust my diet, I used to have horrible gas cramping and burping. Drinking a little water with raw cider vinegar would usually relieve the pressure. So I carefully syringed Rusty a dilute of ACV, and I could hear the gas in the crop breaking up. And her open eye brightened and her tail went up. So I think this gas is causing her pain and that's why she doesn't want to eat very much. Burping, if it keeps happening, hurts. And makes it hard to breathe.
This morning's update gives some creedence to my theory. First thing, I gave her a cc of Clotrimazole at 5:30am and a crop massage. An hour later, I gave her the antibiotics. Just now, I mixed up a little damp mash with probiotic. She was hungry and went for it.
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She ate about a TBLSP of it, then she lifted her head to swallow, paused, and burped hugely. It looks like this, and she's definitely pushing out gassy air, it smells like bread baking. The smell is more sweet than sour.
View attachment 3698411
She actually ate a little more after that. Now she's trying to digest. She also just made a reasonably ok poop, considering everything.
So I'm thinking:
The infection seems under control. No more discharge or acrid smell. No swelling in the abdomen or vent. I'm going to keep her on the amoxy/ceph though for 10 full days because I don't want it coming back like it did when I stopped after 5.
The sweet smell tells me that her whole system has become too alkaline, her Ph is too high. The ACV in water (I made it pretty strong 1/2 tsp in a cup of water), brought her immediate relief. That's good information. She clearly needs probiotics as
@azygous recommends, but her system needs to be acidified because good bacteria can't live in an overly alkaline environment.
I've never had luck with Nystatin either. Right now, based on what I'm seeing here with Rusty, is to keep her on Clotrimazole 3x day. Help her burp. Acidify her system. Give probiotics.
And feed her things that don't produce gas. The mash I'm giving her is grower feed, but I know it's got soy and soy can make gas worse. I'm in a remote area in Ecuador, there's no designer soy free feed. Or baby food. (I'm thinking just mashed egg yolk might be the way to go.
Thanks so much for your encouragement and insight everyone. Realizing that her crop is filled with air and more "sweet" than sour, feels like a key to being able to help her better.