It does sound like a stomach flu. My twins were premies and have been really prone to this over the years. So, we've become pros at this. I help them while they're puking, husband cleans up. What you need to do (and of course it's hard with that little of one because they don't understand)...but give them room temp gatorade, NOT WATER, give it to her 1 tsp every hour and that's it. After a couple of hours if she's keeping that down go to 2 tsp and as long as that goes well, then move to every 30 min. Don't worry about her not eating, totally not a big deal!!!! If she doesn't want it, don't worry!!!! She's not hungry. I don't know what area you're in, but right before x-mas there was a nasty stomach bug starting to go around.
Also, is she still having wet diapers? If she is, then she's not getting dehydrated. If it gets a dark color or doesn't have one all day, then she's heading towards it. Goodluck, it will get better soon. If this is the first bug she's had then it's always scary. It will get better. Also, my daughter would always take about 2-3 weeks after having a flu to get totally better. It would trigger her oral sensory issues and some things that she totally would eat, she would gag on and throw up. Also, if you haven't been told, do very bland foods, toast, crackers, applesauce, eggs, etc. Goodluck