C.,
You are absolutely doing the best thing for your daughter by nursing her. She does not need water or Pedialyte. Your breastmilk will provide the perfect balance of nutrients (which both other liquids lack) as well as help boost her immune system (which the others will not do). She will not become dehydrated as long as she is nursing, which is the only reason doctors recommend pushing other liquids. Also, by offering other liquids, you will be cutting down on the amount of breastmilk she is taking in, which is not good for her especially while she is ill. There is also no reason to push solids on her. Babies do not need anything other than milk for the first year of their lives. Solid foods at this point are more in the nature of experimentation than actual nutrition! And again, if her stomach is upset, solids are much more likely to make it worse than breastmilk would.
As far as the nursing/vomitting goes, it is probably just the flu hanging on. The one my DD just got over has been going for around 2 weeks. (Started w/a few days of vomitting, but then turned into weeks of diarrhea.) You might try nursing off just one breast for a few hours, then switch to just the other breast. There can be a problem with offering a limited time on each breast. The milk that comes down early in a feeding (foremilk) is fairly thin, and high in protein and carbohydrates while the later milk (hindmilk) is creamy and high in the fatty complexes that she needs to feel full, stay full, and fuel brain growth. If you limit nursings to a short time on each breast it can actually contribute to an upset stomach and also keep baby from getting filled properly, because they are getting only foremilk and not hindmilk.
Whenever I have had to limit feedings for my little ones (mostly in the same situation - trying to get less milk in their bellies so they don't throw it all up) I have limited feedings to one breast, rather than letting them get just a little sip from each breast.
If you still have problems, you can contact your local La Leche League leader. They are wonderful resources, and their advice is free. I hope your daughter is feeling better soon.
Best of luck,
S.