Hello  ,decreased urine output  could  be due to less water intake,  ureteric  stones,  Gastritis is the most commonly seen problem these days ..  Medicines can only give temporary relief.. Strict diet and lifestyle change can bring gastritis under control. Avoid spicy, hot ,high protein containing foods like fish  .Take dal rice , butter milk ,curd rice ,drink plenty of water , have frequent small  meals instead of large regular meals.Sleep 2-3 hours after having dinner .Take antacids and ppi for temporary relief.