What exactly is your question? Do you want to know what to give a 2 year old with gastro?
If so, the best thing to do in a case like this is to give him water-rich, easy-to-digest foods when it is time to reintroduce food. In the early stages of a stomach bug, your child may not want to eat, so just make sure he or she doesn't get dehydrated. Offer water and rehydration solutions such as Pedialyte™. And watch for signs of dehydration (dark or absent urine, dry mucous membranes, loss of energy, etc.).