hi i had gone through your query and understand your concerns. i would come up with two possibilities.
1.the possibility is, MOUTH ULCERS;
-Stress or tissue injury
-nutritional problems, such as vitamin B-12, zinc, folic acid
, or iron deficiency
-gastrointestinal tract disease, such as Coeliac
disease and Crohn's disease
-Certain foods, including citrus or acidic fruits and vegetables (such as lemons, oranges, pineapples, apples, figs, tomatoes and strawberries), can trigger a mouth ulcer or make the problem worse.
2.second possibility is,ACID PEPTIC DISASE;
-smoking and drinking
-lack of physical exercise
-taking NSAID and steroids
are some possible causes
I hope this is helpful for you, thank you