You poor thing, it's the worst! I think just whatever you can stomach while your unwell, your body has a way of evening things out after unusual periods of eating poorly, so long as you don't make a habit out of it long term.

Since I've had morning sickness I've found Gatorade non offensive and helpful with hydration if I can't stomach water/proper food. Also watermelon but you probably don't want to overload with fibre when you have gastro :/