Burning sensation

Hi All , For the past 4 years I am suffering with the below symptoms .
Initially I got a burning sensation 2 to 3 inch below my belly button and slowly it started to move around . The burning sensation moving all over the intestine and stomach .Sometimes ppi worka but not always . Especially it irritates when I have slight spicy foods . If the burning is there in lower part there won't pain in any other area when it moves the pain won't be there in prior place. Also the pain will be mostly below the right rib . Most of the time the stool will be normal but when the burning pain is severe some time there will be constipation but most of the time it will be normal .Also when the burning sensation is more there will be burning sensation while passing stool ..I consulted almost all the top consultant s in Chennai India but no one is able to pin point the issue .The issue started when I was following below ie before 3 years .One dr told me that it is IBS and one dr told it's neuro issue and one another dr told me that it is functional dyspia .Endoscopy was done 3 times , colonscopy , hpylori test, food allergy test MRI - ct Scan was done twice but not able to diagnose correctly ..can someone help me on this ?