There are a number of possibilities
1) Stomach has peptic ulcers – Severe pain will be there, reduced by food in-take. Take a simple blood test to see if you have H. pylori in your stomach. If yes treat it and the problem should go away. Pylori may easily transfer between family members.
2) If drinking milk or eating a milk-based product causes gas problem it is a case of lactose intolerance and easy tests are available.
3) Also see if you have aerophagia (unconscious swallowing of air). This may be tested by placing (chewing on) wooden sticks or pencils between upper and lower jaw, to avoid swallowing of air.
4) Also eat slowly and chew well and concentrate on eating (No TV while eating). Never eat while lying down - Sit straight up and eat (Grandma`s advice). Avoid carbonated drinks or carbon dioxide producing acid suppressors.
The food escapes from Stomach to small intestine, only when they are ground down to about 2 mm in size.
Stomach mean while keep producing acid to help it digest. So help your stomach push the food out faster by grinding it down as much as possible in your mouth (this is esp true about hard rind/skin fruits) so that nature does not have to send it back up like in goats or cows!!! No offense meant. (Nature has provided stomach as a temporary storage of food in these animals so that they can chew leisurely later after gulping down the grass but not so in human beings!!!)
Eliminate the possibilities by trial and with the help of your doctor. Good luck and take care.
Nature has answers for all, but our job is to find the diamonds among coal.
From Asprin to Viagra all comes from Nature.