2 years back, I also have gastritis. To be honest, all the pills that I ate hardly have any effect. Mine wasn't very serious but there is discomfort throughout the day.
It finally disappear after 2 or 3 months. I guess it heal by itself

Do not eat spicy or oily food. Drink water, eat balanced diet. Exercise. I'm not sure if any of these help, but there is nothing wrong to adopt a healthy lifestyle