Calf manna will help put weight on. It is 25% protein. I would start her slowly then move her up to 1 lb per day. I would also make sure there isn't anything else affecting her weight such as worms, lice, etc. You could try copper bolusing her to help with the rough coat if you haven't already.
Does she have any black fur? Only black fur will turn reddish, in my experience. My Nubian wether is red and white, and I noticed his coat felt rough and his hairs started to curl before I first bolused him. He was also having some of his red fur fade to white, Fish tails are a definite sign.
I'd give a copper boluse as well as worm her and add the calf manna. Even with loose minerals, and feed with in it copper it's very rare that goats don't need at least a dose or two a year.
We found this out the hard way. We had a doe with twins go down hill very fast, and we lost her. We had her UTD on wormer but she didn't respond to the wormers because she was low on copper. At first I thought she was starting to look poor because of the two bucklings on her. When we realized she was not responding to the wormer we pulled the kids off of her and reached out to some more experienced goat friends. We gave her a mulit min shot, but it was too late....if only I'd known what I know now.
Sorry for the sad story, but I'd hate for you to lose your girl too.
Jeffers now sales it already dosed for goats, and you can pop them open and mix it in oat meal or a in marshmallow.