When my stomach gets empty (few hours after eat) my ab middle does sounds, feels full, mouth tastes different, a bit dry. Eating helps water not why?

Gerd. You may have hyperacidity with refux of the acids the mouth causing taste alteration. Try Prilosec over the counter for 2 wks. if no improvement need to be checke out.
Nondiagnostic. These symptoms are nonspecific and they may be a variant of an irritable intestinal tract or a food intolerance such as lactose or gluten. Your stomach should be empty 2 hours after eating, so any sounds you hear are peristaltic waves moving through the intestinal tract. See if certain foods cause your symptoms. A gastroenterologist is best qualified to evaluate and advise you if needed.