For the one due in May you should think of slowly increasing her ration, so getting her to eat for example more fruit, bananas, carrots and apples, plus cabbage (if she is not being milked) should get her appetitie going again. You could also try a Co VitB12 drench, I think it worked for one of JK's goats that was off her food for a while. However with branches coming into leaf you have a whole other feeding possibility coming up soon.
If you have your GG in the same field as sheep please watch her worm burden. Goats are a lot more sensitive to worms, and unless you are sure about the worm status of your sheep I would not co-graze goats and sheep at all.