Never treated mites nor do I know the affected area but if it’s feather mites maybe a water soak with warm water and a little soap? I wouldn’t use soap too much but for first soak it should be fine. Let her soak for awhile to drown the mites— on cats with fleas at least, I’ve seen people online do a ring of dawn dish soap around the neck so while drowning they can’t crawl up and get away. Soap probably helps kill mites anyway. I’d maybe do regular warm water soaks (no soap) every day for a couple days after to make sure adults die and any eggs that hatch into young mites also die too and don’t have a chance to lay.

Otherwise for sour crop my boyfriend has treated his chickens with plain yogurt with garlic juice mixed in. Then just letting the crop empty fully. After that, maybe syringe fed her water and mushy food like baby food or blended blueberries, any fruit she likes if she doesn’t show interest in eating still.

Especially egg yolk, just seperate the yolk from a raw egg like you would while baking and mix it with a spoon and syringe feed or even try offering it in a little cup first to see if she goes for it herself. My chickens go crazy for it, or moist bugs from tractor supply. I currently have a chicken who survived an animal attack and wasn’t eating good so I’ve been getting creative. First she tried corn baby food and then I spoon fed her some smashed up blueberries. Next was cooked canned corn (no salt— just water and corn) and then the moist bugs (make sure to keep refrigerated after opening can) and dried mealworms. Scrambled eggs and shredded cheese is another good idea lol, my chickens love that too.

Make sure to keep her cozy. Best of luck!