I am so sorry that Audrey isn't getting any better
Can I make a couple of suggestions? You can ignore me if you like, but I'm thinking you have to get that girls immune system up.
Most important, I would add some coq10 to her diet (2mg per pound of body weight). nuVet suggests thumping the thymus gland (on the chest, dead center between the front legs) 5-10 times once a day. He says this stimulates the thymus which boosts the immune system too.
You could also add some immune boosting fruits and vegetables to her diet (yeah... I went there lol) Oranges, Cantaloupe, Strawberries, Blueberries, Spinach, Broccoli, Carrots, Bell Peppers, and yes.... Sweet Potatoes :D All of these are high in easily digestible, natural vitamins A, C & B and antioxidants. The bonus would be that the vitamin A would help her skin (maybe even toss a daily vitamin A supplement in there until this all clears up)
nuVet also told me to get one of those thin wire brushes and brush her twice a day to distribute the oils and stimulate blood flow to the skin.
I took Abby off the Ivermectin when she had that reaction to it. I added the coq10, bought the brush and started thumping her thymus and the mange cleared up on its own (she had already been eating those vegetables). I know that Audrey is sicker than my Abby but it's worth a shot isn't it?