Gas problem. Something really serious?

I am a student and I have to eat out  everyday,I eat at 2-3 different places.I have gas problem,nausea ,urge of eating now and then, if not then severe cramp like pain in stomach and flautance and heartburn symptoms ,bitter mouth like since last year and initially doctor prescribed antibiotics and ppi and symptoms subsided with that. But again after a 3-4 months I got the same symptoms and I went to the same doctor and he asked me to do blood tests and usg  abdomen and endoscopy, everything appeared normal so he told me to continue with same tablets for a week and my symptoms subsided. Now again after 6 months I am experiencing the same symptoms and when I get these symptoms even my stools aren't normal,and I have to frequently go for it and I also experience anal itching .Should I again continue with the same antibiotics and ppi or is it something really serious? Please suggest me a remedy for it . Oflaxcin o, bandy plus,sonata powder and nexpro rd 40 are tablets I was prescribed with