Simple sugars like glucose, fructose, lactose, fructans from wheat and galactans from legumes  often cause bloating, flatulence and diarrhea. Low FODMAP diet may help:
http://www.healthhype.com/fodmap-diet-foods-to-avoid-in-ibs-bowel-disorders-with-bloating-and-gas.html

UPPER ABDOMINAL BLOATING with EARLY SATIETY and BELCHING (but not flatulence or diarrhea) is often triggered by:
1. Helycobacter pylori infection of the stomach. Dx is by urea breath test for H. pylori.
2. Gastroparesis (slow gastric emptying). Dx is by stomach emptying test.

Diet changes don't help much. Avoiding acidic foods may lessen stomach burning and heartburn.

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OVERALL ABDOMINAL BLOATING with FLATULENCE and/or DIARRHEA (and possible belching)

Two common food-related causes of bloating are fructose malabsorption and lactose intolerance. Elimination diet trial may reveal the cause.

1. 4 days LOW FRUCTOSE DIAET TRIAL in suspected fructose malabsorption:

Avoid all fruits and fruit products, honey, wheat, onions artichokes, leeks and any product containing fructose, HFCS, sorbitol or other "polyols" like xylitol, maltitol or mannitol (in "sugar-free chewing gum", "diet sodas" or "low calorie foods")  
Details:
http://www.medhelp.org/user_journals/show/21247?personal_page_id=801

2. 4 days LACTOSE-FREE DIET TRIAL in suspected lactose intolerance

Do not eat any food containing lactose that appears either as a natural ingredient in dairy products (milk, cheese, butter, yougurt, cream, ice cream) or as an additive in many pre-prepared foods and even pills.

You may join both diet trials together - plus avoid any sugar of any kind. This way you get a "low-FODMAP diet" (search online). This diet trial (low-fructose + low sucrose + lactose-free) should also last 4 days. If, after 4 days of low-FODMAP diet your symptoms disappear, you (on 5th day only) add wheat, onions, leeks or artichokes (containing fructans) and continue until 8th day with low-FODMAP diet. If all OK, it means you can safely eat wheat, onions, leeks or artichokes. On 9th day (only) you have some milk (1/2 l) and continue with low-FODMAP until 12th day. If all OK, you are not lactose intoleran but if symptoms appear then you probably are. On 13th day (only) you add one orange, grapefruit, banana or kiwi (low in fructose) and continue until 16th day with low-FODMAP diet (and dairy, if it triggered no symptoms). If all OK, on 20th day (only) you add "one portion" of berries (strawberries, blueberries..) and continue with all food that was OK until 24th day. On 25th day (only) you eat one of these: few plums, prunes, one peach, apple, pear or black (not white) grapes and continue with all safe foods until 29th day. If you have fructose malabsorption these foods will likely cause bloating and/or diarrhea. If you already know this, no need to try.

The rule is to give any food type 4 days to see if symptoms will appear (if they will, they will usually appear within 2 days but 4 days is to be sure and to not mix effect of different foods). When you add a new food you eat it only one portion and only one day - so only once.

Before strat all this be sure to have exact lists of low/high fructose foods, lactose-free foods and write down the whole eating plan in advance. If symptoms appear you will know that they were from the last food you've added. In this case just wait until your symptoms go away completely and then continue with the trial.

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Official tests, performed by gastroenterologist:
- For fructose malabsorption: hydrogen breath test with fructose    
- For lactose intolerance: Hydrogen breath test with lactose
- For small intestinal bacterial overgrowth (SIBO): hydrogen breath test with lactulose (or xylose)
- For parasites: stool test: Ova & Parasites

Many people with bloating and diarrhea get diagnosis of IBS. But actually they may have frucose malabsorption - FM (or lactose intolerance or celiac disease) in which some fruits, vegetables, sugars and other products rich in fructose or sorbitol can't be tolerated. The problem is impaired absorption of fructose and sorbitol in small intestine. Treatment is with low fructose diet.
http://www.healthhype.com/nutrition-guide-for-fructose-malabsorption.html

Problematic nutrients in FM are: FRUCTOSE, HFCS, SORBITOL and other POLYOLS (maltitol, mannitol, xylitol) and, only in some individuals FRUCTANS.

Most problematic foods are:

- FRUITS: apples, pears, prunes, peaches, sweet cherry, dates, raisins, mango, papaya.
- FRUIT JUICES, JAMS, COMPOTES.
- HONEY
- SUGARS and SWEETENERS: fructose, High Fructose Corn Syrup (HFCS), sorbitol, xylitol, mannitol, maltitol, raw sugar, brown sugar, molasses, Splenda.
- "LOW CALORIE" FOODS AND DRINKS and "sugar free" chewing gum with added sorbitol or xylitol
- WHEAT (contains fructans)
- VEGETABLES: onions, tomato, Jerusalem artichoke, leeks


Low Fructose Diet Details:
http://www.healthhype.com/low-fructose-diet-in-fructose-malabsorption.html

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Those who have ONLY FM without lactose intolerance, small intestinal bacterial overgrowth, celiac disease or intolerance or allergy to some specific food CAN PROBABLY SAFELY EAT:

1. The first thing when you have FM is to find out if you can tolerate foods with fructans: WHEAT, ONIONS, JERUSALEM ARTICHOKES, LEEKS. Most of affected persons can at least in small amount.

2. BREAD and PASTRIES of any kind - without fructose or HFCS
3. CEREALS, CORNMEAL, OATMEAL and the like - if nonsweetened
4. PASTA
5. MEAT - but there is often fructose in breading and some packaged meat products are sweetened with HFCS
6. FISH - canned fish may be sweetened
7. DAIRY - if nonsweetened
8. EGGS
9. VEGETABLES, except sweet ones like beats, cooked carrots, sweet potatoes, canned prickles, etc.
10. Many persons with FM can safely eat BANANAS, ORANGES, GRAPEFRUIT and LEMONS (low in fructose). Many can also eat all kind of berries.
11. PLAIN or MINERAL WATER (nonsweetened), NONSWEETENED TEA. FRUIT JUICES from above mentioned fruits may be ok. DRY WINE and other NONSWEETENED ALCOHOL in limited amount may be ok, but it can aggravate SIBO so find out by yourself if it triggers symptoms in your case..  

Glucose and sucrose - table sugar are not recommended despite the fact that they help in absorption of fructose because they are often not tolerated and may cause small intestinal bacterial overgrowth (SIBO).

If your burps or gas smell like roten eggs (sulphur), try to avoid sulphur-containing foods, which are basically all animal foods except fish. Some vegetables and especially many sauces and salad dressings contain sulphur. Check for detailed list here:
http://www.healthhype.com/sulphur-or-rotten-eggs-burps-belching-foul-smelling-gas.html