Hi. Thanks for your query. Noted the history about your Father and understood the concerns. Stomach pain with diarrhea since Thursday beginning spontaneously at night and not improving indicate that there is an intestinal infection. I would advise him the following: Clinical evaluation and examination by a Doctor to know the vitals and abdominal examination will tell if there is any perforation or such a problem that needs emergency management. Send stool for tests. Tests of blood and urine. Ultrasonography of the whole abdomen. X-ray of the abdomen in standing position. Get started with proper antibiotic active against intestinal infection and add-on metronidazole, probiotics and so on as needed. If there is a surgical cause, he will need surgery to relieve the problem. If this is a medical problem the above medications will help him to recover well. Give him boiled and cooled water. Fresh home-made food only. Plenty of oral fluids to avoid dehydration. Electrolyte solution to have proper balance of electrolytes.