Hi Sir I Am Suffering From Gastric. Since A Week

Hi Sir I am suffering from gastric. Since a week time my belly is becoming big due to gas generation and it is uneasy to me. I had been taking happi tablets and day before yesterday I changed it to omiprazol 20 mg. Yet don't feel much deference. NO much heart burning or acid generation. at the moment. Please advice me for better medicine. Thanks Nihal J.