You could try adding some soya oil to her feeds. Start by adding about a table spoon full and work up to about an egg cup per day over a period of about 2 weeks, Give it any quicker and she'll just get diarrhoea.
Let her out to graze for as long as possible, grass is the best and most natural feed for horses, and don't worry about laminitis, if she's never had it she wont get it now!
Also worm her, if she's not been wormed recently both for round and tape worm.
Good luck, and a big pat from me.