Hello... Welcome to healthcare magic... According to your complain you have problem of diarrhea and abdominal pain that may be because of gastroenteritis problem.... Stomach ulcer may cause abdominal pain problem...... Infected food also cause this type of symptoms.... Consult a gastroenterologist for further diagnosis. Stool examination test help to detect any infection present or not.... Complete blood cell count and microscopic examination is helpful... I hope my guidance helpful to you... Take care. Thank you.