I've been suffering from gas every evening from past 3 months, what might be the reason. i am not fat and maintaining a healthy weight. only thing which is worrying me is excess gas?

May be constipation-eat greens-, diet -beans cause gas, or food intolerances, check for lactose or gluten sensitivity. ( can be other food as well) or irritable bowel or other GI issues ( early inflammatory issues, r pancreatic insufficiency - though that is associated with diarrhea) Check for intolerances by eliminating the food from your diet for 7 to 10 days and see if change. F/U GI