Kombucha could help with gastric issues because the organic acids and probiotics in Kombucha promotes healthy digestion by getting rid of the bad bacteria and replenishing the good bacteria. You could try to see if it helps.
But as always, start slow first with about 50ml-100ml and diluting with water as needed to see how the body feels. If there is improvement, consumption can be gradually increased. If symptoms worsen, please stop / cut back for a while as the body might take a while to adjust.