Hi thanks for contacting HCM.... Yes stress as obvious can lead to loose stool and gastritis ........ So Try to avoid stress .... If needed you can take help from psychiatrist for behavioural therapy ... Yoga helpful..... Second apart from stress rule out h.pylori infection by urea breath test.... Here by stress functional bowel disease can be there ....... When diarrhea maintain hydration.... Probiotic can be taken..... Hot water and youghurt can help in upset stomach... Kiwi rich in linolenic acid , vitamin E , magnesium , pottasium , actinidin etc.....so can be taken for proper digestive function... Avoid gastric irritants like.... -tea , coffe -alcohol -smoking -meat etc.... If needed you might prescribed proper antibiotic.... If still symptom worsen USG and stool examination done.... Take care....