Wheatie, As long as you can get Lucie to keep some water or even juice in that will help her. I wouldn't even bother with formula atm if she is only bringing it back up. As long as she can keep some liquid in you will avoid dehydration. Do you have ice blocks?? If so give her them to suck on. You can get ice blocks that replace electrolytes in her body. You can grab them from Woolworths and the like.

I hope that Lucie is feling better real soon. Goodluck today at the Dr's.
We have had the same bug going around up in Sydney too.