hello, your daughter seem to be suffering from acid peptic disease due to over production and secretion of acid (HCL) in stomach which leads to gastritis and gastric ulcer formation in stomach , on taking food, food in stomach stimulate more acid production and acid irritate the ulcer area cause pain and sudden contraction of stomach cause vomiting and excess acid leaving the stomach to lower bowel early without mixing properly leads to loss stool treatment is first to change your life style that is avoid spicy and oily food, avoid coffee and tea especially empty stomach, drink cold milk , eat mint etc. there is lots of antacids medication for neutralization of acid in acute condition like ENO and medication that decrease acid secretions like pantoperazole , lansoperazole etc taken on empty stomach two times for 4 weeks than taper to once daily than withdraw slowly with diet modification