You could try some peppermint or ginger. You can make a tea, there's gingerale, or peppermint candy sometimes works. Also, a slice of whole wheat bread kind of soaks up acid, or really just a dinner roll or any bread works. Take a roll of Tums with you, that will almost always make tummy acid stop.
As for something you've been eating, I've been eating some store brand cheese squares that are tearing up my stomach, and also store brand sodas will do the same thing.