I swished some seltzer water in my mouth yesterday, and it hurt so good around the gums. It felt like it was cleaning my gums and preventing canker sores from forming, but who knows. Regardless, I wonder if they can make a carbonated mouthwash that you can swallow. Similar to this product pictured (just minty water, found at PSFK), but carbonated, with natural substances to freshen your breath, like mint and baking soda or something. Once you swallow it, maybe it settles your stomach as well, somehow (with ginger and stuff).

A Google search yielded this similar patent.