Hi! We are almost neighbors; I'm in Arlington! Anyway, funny to read your post because my 3-year old has had the stomach bug since last evening. In fact, though she seems a little better this morning, we have a holiday party with friends and kids planned for tonight here at our house and will probably have to cancel! I would feel awful if I went somewhere and one of the family members in the house had been vomiting. My experience with my two kids is that it sounds like your daughter has a little stomach bug (they are EVERYWHERE right now), but maybe the initial vomiting made her feel better because it always feels worse before it comes out! I would wait and see how she is this morning, go easy on the milk or don't offer it at all, and stick to watered down apple juice or Pedialyte if you have it (many will say no juice because of the acid, but neither of my kids ever drank Pedialyte and when they were sick like this, watered down juice was all they'd drink). Try to give her foods that are easy on the stomach, like toast or a waffle without butter or dry cereal. The longer she goes without vomiting, the more regular foods you can try on her. Also, some fluids are ALWAYS better than no fluids. My daughter is drinking ginger ale right now but she never liked it when she was under 2.
These bugs can be fast and basically gone with just one or two vomiting sessions, or they can linger 24-48 hours sometimes. My 5-year old had this three weeks ago and it was gone quickly... hoping it's the same strain for my little one. Good luck!