Hi, There are different possible causes including GERD, use of gas-producing foods, food intolerance, lactose intolerance, constipation, and celiac disease (1) GERD- gastroesophageal reflux is one of the most common causes.It is treated by the medications that you mentioned which take 5 to 7 days to have an effect because they prevent acid production from the stomach but cannot get rid of the acid already present. So when this acid that is already present leaves the body then the effect of the meds is felt. GERD also requires diet changes with the medication- (a) small frequent meals rather than large meals (2)no citrus fruits including tomatoes and tomato products, coffee, onions, spicy foods, fried/fatty foods (2) use of gas-producing foods- broccoli, cabbage, turnips, peas, beans, prunes, Brussel sprouts, carbonated drinks, pears, peaches (3) food intolerance - if there is intolerance to any foods it can this symptom (4) constipation (5) Celiac disease (6) Lactose intolerance Treatment would involve: (1) Reducing the use associated with increased gas production (2) Continue the use of one of the medications mentioned (Prevacid or omeprazole). Use consistently (3) If no effect consider if lactose is intolerant or if there is any food intolerance. Hope I have answered your query. Let me know if I can assist you further. Take care Regards, Dr Ivan R. Rommstein, General Surgeon