Hi and welcome.
There is most likely gastritis that is inflammation of the stomach and it usually follows intense diarrhea. I would suggest you to take bland diet for about a week, take OTC antacid and omeprazole available OTC 10 mg twice a day. Avoid smoking, smoked and spicy food, If symptoms does not improve then do visit your doctor for thorough physical examination.
Let me know if you have further questions.
Wish you good health.
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