oh, dear. poor babe! um.... could you start with watered down fruit juices, then make really really thin and well blended soups (with a good veggie stock so at least there is some nutirents in them!), and thin fruit smoothies, and offer them as a drink, gradually making them thicker over the course of a week or so? then move up to creamy mashed potato and rice pudding and fruit puree and things like that, till she gets used to the idea and looses the fear of throwing it up again?
does she have a favourite soft cookie type that you could make into 'gloop with some milk, or could you revert to rusks and milk for a bit? i loved rusks as a kid, and cos they melt in your mouth- not too scary! melted icecream and sorbet might work too?
you can get electrolyte powders to mix into water- that would be a good idea, might perk her up a bit, and support her body while it gets better, definately more so than plain water.