Ds (3) has never had a tummy bug as such. He's eaten something that disagrees with him, thrown the day's food up and been fine afterwards. But he started vomiting last night, bringing up dinner, then his milk, and then all the little sips of water he'd taken through the night, about every half-hour or so. He wants to eat and drink, but even when restricted to plain toast and water, it's all coming up. This is new to me, the bringing-up-water thing, and for it to be going on for almost 24 hours. I'm primarily concerned about him becoming dehydrated. Any thoughts? Thanks.