Well come to HCM Thank for asking to HCM I really appreciate your concern, formation of flatus could be due to diet or the infection, first thing you need to do is to change the diet avoid beans, fatty food, oily food, grams, and rule out the infection, in case of infection it has to be managed accordingly, if I would be doctor of this case then I would treat it with Tinidazole 700 mg twice in day for 5 days keeping in mind that it could be giardiasis and it is the empirical treatment else the stool needs to be sent for routine test, looking to the history of malignancy I would advise you to discuss this with your doctor this information helps.