Simple tomato sauce (fresh minced garlic, crushed tomatoes, salt and pepper to taste)
Chopped kalamata olives
Wilt spinach into the sauce just before serving -- you can chop it smaller to make it easier to digest or even skip it if you think it might aggravate your stomach
It goes best with a penne or fusilli -- something that will grab the sauce well. Top with parmesan.
You can also throw this in a baking dish with mozzarella or ricotta and parmesan and it makes a good baked pasta dish. But if recovering from a stomach bug, I'd keep the cheese to a minimum.
Hope you feel better soon, OP.