If it is a virus/stomache bug, it needs to run it's course. Keep them hydrated and hold them when they need you to. My doctor has always told us to stop all milk products immediately and follow the following guideline:
Day 1 - CLEAR liquids only...Gatorades, Pedilyte, Chick broth, juice, koolaids, flat soda, etc. Once they can keep these down...
Day 2 - Add fruit...apples, bananas, etc (watch out for applesauce because that can cause loose stools too). Once they can keep these down...
Day 3 - Add vegetables...Once they can keep these down...
Day 4 - Add grains/Cereal...Once they can keep these down...
Day 5 - Add meats....Once they can keep these down...
Day 6 - Normal except no milk products....Once this is handled well
Day 7 - Milk products
If at any point the vomiting resumes, regress back to day before.
My kids usually skipped ahead and we would add fruits and vegetables at the same time. Also, if they wanted grains early I would let them but they had to handle the other stuff well before I would add milk products (hard to digest).