It sounds like post-infectious irritable bowel syndrome. It usually strikes those who have IBS in the family (my mom has it). Before my first trip to South America, my stomach was mostly agreeable with only minor issues when I'd drink coffee or eat tomato sauce, but after it has been extremely sensitive to a whole lot of foods. I have to seek lodgings with a kitchen because eating out will usually end up with serious problems. The symptoms will fade with time but in my case it has not disappeared.
If I were you I'd first try probiotics. The nuclear bomb of probiotics is VSL 3. Another good choice is Kirkman Pro Bio Defense. Stay on those for at least a couple months and fade them out if they're working. You should definitely see at least some improvement.
If that doesn't work, you have to change your diet by identifying trigger foods. This means you will be able to eat less selection than before, but the benefit is your symptoms can be managed. These are my trigger foods that I should avoid:
-Coffee
-High fat ground beef
-Dairy
-Garlic, onions, broccoli
-Green or red peppers
-Pizza
-Tomato sauce (but ketchup is okay)
-Alcohol (especially on an empty stomach and especially beer)
-Butter
-Avocados
It has taken me a couple years to figure this list out because symptoms from a food don't come immediately after eating it. Depending on the portion size and what else was in the meal, isolating is tough (google elimination diet).
The best resource is
http://www.helpforibs.com/. She understands the problem better than doctors. Sign up for her newsletter and find her trigger food PDF. From her I learned:
-Pop a peppermint or fiber pill before eating if your stomach is unhappy or before a dangerous meal. Peppermint is very soothing.
-Eat the safe items first before the bad. So in a meal I'd eat the rice before the red meat, for example. Or the banana before peanut butter. Rice is my safe food, and a big chunk of my diet.
As a result of this, I almost never eat out. If I were to take a girl out to dinner (at a place with buttery dishes) and then go drinking afterwards, my stomach will in bad shape by the end of the night when it's time for
. It's a shame but that's life. On the plus side, all of my meals are cooked and I eat healthier than before.