Hi, Noted the detailed history about your 4 year old son and understood the concerns. He is already under investigations and treatment for recurrent diarrhea, and vomiting out of which some symptoms got subsided. The probable cause can be found out by the following ways in addition to the investigations already being done: Repeated stool tests for three consecutive days sometimes help to get a proper diagnosis and thus a proper management. Amoxicillin and Clarithromycin are drugs of choice in H pylori but not good for intestinal infection wherein other medications like Cefixime and Ofloxacin work better. Add on probiotics. Identify the foods and beverages that instigated the problems again or enhance the symptoms. Stop milk and milk products. Add on Metronidazole for 5 days under the prescription of a Pediatrician. Ultrasonography and CT scan of abdomen may help to find out other causes like Abdominal lymph nodes and so on. Colonoscopy may be needed. All these things together will help to get an appropriate diagnosis and have proper management. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. T Chandrakant, General Surgeon.