Ginger Ale helps settle the stomach, Vernor's brand if you can find it. And a simple diet. For babies, you use the BRAT diet: B=bananas, R=rice, A=apple juice, T=toast (no butter!). Basically clear liquids, anything you can see through. Chicken broth. No dairy products.
It might be the stomach flu, and just needs to run its course. But the fluids will help you get better soon.