Hello sir. Are you on any kind of medication? Often many medications cause gastritis. Other than that also I would recomend you to take a PPI or H2 blocker daily. Like Pantocid, Rabekind, Reekool, Esozol etc. 1 tab daily empty stomach. Also this is most often caused by spicy, oily foods. Avoid such kind of foods. Eat light in multiple meals. Increase your fruit intake.
Next Steps
if problem persists then an ultrasound abdomen is advisable.
Health Tips
I can also suggest homeopathy if you wish for alternative medication for bloating and gas