Hi! I hope she feels better soon.

I agree that the med syringe trick is pretty effective. Just aim for the inside back of her cheek and try squirting 5ml at a time. You might try to get some flavored Pedialyte into her that way. It really perks up my child when she's feeling bad.
I also agree with the slurpee idea. Just spoon feed her that or ice chips, or bites of popsicle (cut it with a knife into tiny cubes) instead of the whole bar.
If you notice her going downhill more, but she's not to the point of needing IV yet, ask the ped if she can get a shot or suppository of that anti-nausea med. It really works with my kids. They start to feel better very soon and then are willing to drink again.