If your stomach is hurting because of excess acid or acid reflux, then Tums or Rolaids or a generic antacid should all work fine. Chew it up a little and chase with water. No real danger in eating two instead of one. If your acid stomach persists for more than a few days, see a doc. If it's something besides acid making your stomach hurt (gas, whatever), then antacids will probably not help at all.