I know when I had a 24 hour stomach virus (well 24 hrs of vomitting) it took me over a week to feel well enough to eat more than jello, applesauce, crackers and toast. I lost a lot of weight in that week.
What does your daughter say about why she's not eating and about how she's feeling?
If you're desperate, have you given her the option to eat whatever she likes?
I would press your ped harder about finding a solution. A liquid diet isn't the best diet for an active 8 year old
K - that wasn't the flu. Flu doesn't come and go in 24 hours. Do you know why she is only drinking, and not eating? It may be that she has an internal parasite that is making her stomach hurt.
It may be that she's developed a revulsion to vomiting, (which is SO COMMON in girls her age!) and to avoid vomiting, she's stopped eating.
Does she say she has no appetite?
I think you need to find out why she's stopped eating before you can go forward.
Best wishes.
To make sure she is getting vitamins perhaps there is some nutrition shake available for children that she may like to drink? Prepare some of her favorites, but try not to put stress on her over food if she doesn't eat the foods right away. Over time she will decide to eat regularly again. If not, give the doc another call.