I take three different kinds, Alka Seltzer
for gas that hurts, then Tums like your meds
for when acid gurgles and burns, and the third is prescription Hyocycamine for when deep in my guts things get strange.
You could ask your doctor to change your medication, but I think it's your digestion is stopped up from the antibiotics that is overwhelming any good the drugs might do, and so the bacteria from the Activia or Acidophilus should help that, along with extra water and exercise.