I can feel a lot of rumbling gas in my stomach and i have frequent belching. no pain, just uncomfortable gas. what could be the cause? i have recently been told it could be gastritis.

Gas: The symptoms are not classic gastritis(inflammation of the stomach lining) symptoms. I believe you're dealing with either excessive gas formation from dietary issues like lactose or other food intolerance or inability to move normal gas production down the intestinal tract and out the rectum. Try to identify food triggers, avoid gassy foods or beverages. Try taking simethicone 1/2 hr after a meal.