I really doubt that this is a sour crop or fungal infection. Her crop probably will start functioning better as she recovers. Many people treat 5-7 days with 2 tsp Corid per gallon, and an additional 5 days of Corid at 1/4 of the dose, especially when one is especially sick. So, that is 1/2 tsp per gallon of water.
Thanks for the update, I was thinking about you and your babies today. Keep us posted on their progress and give them some lovin' for me! 
