First of all, you have to rule out life threatening things like cancer through traditional methods. That being said, the totally traditional guys are useless when it comes to things like bacterial overgrowth, e.g., Candida. Unless of course you can see someone like Dr. Oz of the Oprah Winfry show. Though recently, a trad doc shocked me with a probiotic recommendation. Any way, Oz knows the best of all venues, not just traditional. If you can find a genious like him, Yippie!
I have had stomach bloating and weight gain since I was a kid. I remember one day in particular when I was 12 years old my stomach looked like I was several months pregnant, naturally, this was while I was performing a part in a play in front of my class. Throughout the years I've found my stomach will blow up at any given opportunity. In short, it can occur from a food sensitivity or allergy, chemical sensitivities, or mold and other environmental allergies.
The fact is that this became a lifelong struggle for me after having multiple rounds of antibiotics due to ear and other kinds of infections as a child. All of the problems I've listed below are said to be a result of an out of balance gut. Even Dr. Oz on Oprah has addressed the issue of gut bacteria, going so far as to say the intestines are our second brain

, thus effecting our entire body.
I've been diagnosed with IBS and GERD. What helped with those problems is avoiding food sensitivities and taking digestive enzymes.
Once again I'm having the gigantic belly bloat and weight gain, bowel problems and chronic fatigue etc. I know this is a result of Candida, bacteria and parasite infections. I tried NAET treatments (used to be allergic with big belly from eggs, but NAET dissapeared it for me), unfortunately I could only afford to go 4 times but require many more visits.
Also amazing are colonics. I've only been able to afford one, but if you had several over a few months and did good diet with no sugar, dairy etc, and good bacteria that would be amazing. I've found that doing an enima with 1/2 lemon and pure water or putting probiotics in room temp water totally deflates my stomach the next day. Also important, you must rotate natural bad bacterial killers with use of probiotics and a good anti candida diet. I just saw a Podiatrist discussing mold and fungal infections with diabetic patients. He said he found that by pulsing the treatments it works better for the patient. That's because our immune system gets used to it and so it stops being effective, so you have to trick it by using different things periodically. Change it up every 4 days or every other week.
I can't afford to do what I know I must do now. Unfortunately, for most people this is a recurring problem that never really goes away, it's only managed. I have seen a website claiming to have a permanant solution to this problem, but I sure can't afford it. If you can then go for it.

Best wishes.