wow, when i read your comment it sounds exactly like celiac disease. i was diagnosed with celiac when i was a young child and had the exact same symptoms you're experiencing. My mother went 50 years before she started having symptoms of celiac disease. She just thought she was having indigestion, but after being tested for it she was found to have celiac just like me. i would seriously consider getting tested. If you do have it you may be doing a lot of harm to your body with out even knowing it.
You seems to be bloated, this comes from gas, which comes from bacteria. It's not necessary from infection, but it can be from bacterial overgrowth in the stomach (this will cause burping) or small intestine. You can ask your GI for BREATH TEST, which can tell, if they are bacteria and where they are.
Lactose intolerance also causes bloating (and diarrhea). You can make a DIET TRIAL, drop all milk products from the food, if you'll get better in few days, it may mean, your have a lack of enzyme lactase, so the milk sugar lactose can't be digested, so it's taken by bacteria, which break it down and produce a lot of gas.
Celiac disease, IBD, and chronic infection can cause the same problems.
Make that trial, if no improvement, doctor can make a stool test for microorganisms, and suggest other tests.