Hi, Thanks for posting your query. With the available described details, there appears to high possibility of Acute gastroenteritis but possibility of melena should also be kept in mind. You should consult with internal medicine specialist/ gastroenterologist and should go for thorough check up. You should also go for complete blood count, blood sugar, serum electrolytes, widal test, amoebic antibodies and thyroid profile. You should also go for endoscopy to rule out bleeding; blood in upper gastrointestinal tract gets coverted to black color due to exposure to acid in stomach. You should take complete antibiotic therapy, antispasmodics, probiotics, antipyretics, if needed. You should maintain your hydration status by taking potassium rich liquids. Take soft diet along with yogurt and banana. Avoid milk and all milk related products. Take care, Dr. Mayank Bhargava