Neither one of those vets sound like they know anything. Your instincts are right. Keep an eye on her with the mite treatment to see if she improves but also to make sure she doesn't have an adverse reaction. I would put warm compresses on her owie, and use a tiny bit of the cream to keep her feathers from getting mucked up and keep an eye on that to make sure she doesnt' have an allergic reaction to that. I am so sorry you can't find a competent vet. My advice to you is stick up for your birds, if in the future, you don't think the diagnoses is correct or the treatment is the right one, politely but firmly decline to have it done. Hopefully now you can get her going in the right direction.
Ginger