Talk to Gastroenterologist on Intestine Gas

Dear doctor i have a gas in intestines not in stomach it remaind all the time not a hard level gas but a moderate level it is from 4 years i have eaten lots of medicine do lot of test but test report negative all the time due to this my blood level in body is 12 low as per my age i am looking too old from my age due to that so plz give me some advice or tell me about medicine that what should i take to recover myself i have also taken zantac,anti gas syrup,siliver for liver,and others intestinal bacteria medicine but fail to got good result plz suggest me something else