What is your diet like? You may have leaky gut. I think that is what I had/have because I had your same problem.
Once I changed my diet (no sugar/dairy/alcohol, caffine, yeast etc. --strict candida diet), started taking anti-fungals, probiotics, and digestive enzymes I felt that the gas went down about 80% or more. I just started recently taking herbs to heal the leaky gut and I think that is what is still causing my upset tummy. You may also have to cut out foods that you are intolerant to.
Also make sure you are not constipated...take herbal laxatives such as aloe vera.
Hope that helps!