What to feed older hen with anemia?

I'm assuming that my 11+year old hen has severe anemia, since I discovered mites all over her. She will hardly eat or drink anything. I try new things every day........she does like yogurt. I've tried eggs, oatmeal, tomato juice, etc. She might take 1-2 pecks at it, but really isn't interested. I have her in a crate. She hardly poops and has lost alot of weight.
My question: What might I buy (supplement) or try to feed her that would help her anemia? Do they have iron supplements for chickens?
I think I got the mite problem under control with wood ashes, but she's just not interested much in eating or drinking........which she really needs to do to get well.
Thanks!