Hello! Thank you for the query. Your symptoms are most likely caused by gastrointestinal infection with urinary tract infection (which appears very often when diarrhea is present). If your stool is black like a tar, and you do not take iron supplements, this can indicate bleeding from stomach. I suggest you to visit a doctor. Blood work, abdominal ultrasound and urine analysis should be done. Antibiotics might be necessary. In a meanwhile please start probiotic supplementation and keep yourself well hydrated. Hope this will help. Regards.