Margo has obviously got run down with being ill, and at this time of year, any lost weight on any animal takes time to be put back on. And you do not want her to go from thin to fat quickly, its better if it can be bit by bit. With seeing her every day, you will probably not notice if she has gained some weight or not.
I have noticed all my goats, and the sheep, are wanting to lick the mineral licks, so they are obvously lacking in something, even though goat mix etc. has vitamins in it. Caprivite supplement to add to the feed has revived my older goats - and they all took it (its a granule type supplement) without any fuss. You would only need to get a small tub, and probably would need to order it at your feed merchant. If you do not have a mineral lick (small ones are about £2.50 from feed store - we use the giant ones with all our gang!) I would get one. Either red or yellow they are.
Have you tried Margo with soaked sugar beet - its helpful for putting weight on. You are welcome to some of ours as I said.
As for her eye, I was reading about that on your other post. I have never had a case of pink eye among my goats, only heard of it in cows. Am I right in thinking it can be passed from goat to goat? Just wondering if the billy you borrowed could possibly be a carrier, and fetched it in? Its not as if your goats mix with anyone else's livestock is it? As far as I know, from seeing it in cows, it can be cured with antibiotics. Just be careful the other goat does not catch it too.
Poor Margo, she has been in the wars just lately. Do hope she perks up.