Hello and welcome Looking at your description, your son might be having acute gastroenteritis with heart disease or another possibility is electrolyte imbalances caused by diarrhea. I would advise you for certain investigation like blood for hemoglobin, CBC, Liver function test, serum electrolytes, stool test for ova, cyst or protozoa. He may require a course of antibiotics like ofloxacin or ornidazole or its combination under medical supervision. Give him ORS, water mixed with sugar and salt, fruit juices and plenty of water to avoid dehydration and correct electrolyte imbalances. Hope I could answer your question, please feel free to ask for follow up question, if you need any more assistance, I will be happy to help you. Best wishes