There could be many things that could trigger the sensitivity in your stomach. Without a complete diagnosis from your primary care physician it is hard to tell for sure what your problem is. However I have found some links and info that may help you.
The first one is a video by Web MD.
http://www.webmd.com/content/article/125/116070.htm
Then there is this list of 10 tips for sensitive stomachs.
Top 10 Tips for Sensitive Stomachs
1. Oranges, grapefruits, melons, bananas and potatoes are best eaten separately, as a small meal all on their own, simply because of their special structure. However eating melons and cantaloupe at the same meal can, cause severe indigestion.
2. Cooked animal proteins and vegetables , or cooked starches with vegetables, are easy on sensitive stomachs.
3. When sugar and protein are combined together, they form waste enzymes which will rot the protein in your stomach and inhibit its metabolism.
4. Cheese and fruit combinations are fine ONLY if you combine some sour fruits in the mix, for example limes, lemons grapefruit and oranges.
5. Pineapple and papaya can be combined with lean animal protein (cheese, chicken, fish) because pineapple contains bromelain and papaya contains papain, two powerful protein-digesting enzymes.
6. Fruits and vegetables are not compatible at the same time and at the same meal.
7. Drinking right after your meal, or two hours later, will dilute your digestive juices and can impair your digestion, which can cause stomach pains and heartburn. During your meals, soup and milk are the least troublesome beverages.
8. Fruits (not acid fruits) are best eaten alone because they are highly alkaline.
9. Hot condiments, such as chili, paprika and even mustard, increase gastric juice secretions, irritate the stomach lining and can lead to ulcers.
10. In general, grains combine very well with dried and fresh vegetables and fruits.
While the above ten tips are very important, its also really important to understand a few additional factors which can and will contribute to your sensitive stomach one way or another. That being said, please also bear in mind the following.
1. Starches require an alkaline medium, which is supplied partly by your mouth and by your intestines. Fats and oils will be digested slowly, mostly in your intestines, and do not interfere much with either protein or starch digestion.
2. You’ll find that sugars are the quickest food to digest; some are even absorbed in your stomach, while most will be absorbed through the intestines.
3. This is good news which simply means that proteins and fats, or starches and fats may be eaten together, as their digestion does not interfere with each other.
4. Proteins and starches are a poor food combination because proteins need an acid medium and starches an alkaline one. These digestive processes are chemically opposed, so when they are eaten together, they stress your system by producing fermentation, flatulence and indigestion.
5. If you’re a young and healthy person with a strong digestion and plenty of stomach acid, you’ll not be affected by protein-starch combinations. However, if you’re an older person or someone with a weak digestion, it will be normal for you to easily develop indigestion, particularly if food is not thoroughly chewed.
6. If you’re like me and you really enjoy a great hamburger with fries, you should be warned. While these two combinations include protein and starch, the potatoes ferment in your stomach and stress it, while waiting for the steak to be digested.
Its really important to remember that correct food combinations are regarded by many nutritionists and chefs as the simplest, most effective way to prevent such common problems as stomach acidity, heartburn, bloating, dyspepsia, headaches, allergies and nervousness. Also people with an extremely sensitive digestion may find the common practice of combining high sugar foods with protein distressing. When you eat a sweet dessert after a juicy steak, for example, the sugar is held up in the stomach until the steak has been digested. In the meantime, for 3 to 5 hours the sugars ferment and bloat, causing indigestion and heartburn. Sugary desserts are best avoided.
To read the complete article:
http://ezinearticles.com/?Top-10-Tips-for-Sensitive-Stomachs-How-to-Avoid-Foods-that-Fight&id=726437
If you have not done so, I would advise you to contact your primary care physician for more information and to be sure that there are not more underlying problems.
Good luck and best wishes.