Hi thanks for asking question. Here are few possibilities in your case. First it can be because of irritable bowel syndrome as you have alternate diarrhea and constipation.Although abdominal pain might be present along with it. Second it can be simple infective or inflammatory condition of bowel. Your stool examination done to see for any pus cell or egg of parasite . Ultrasound examination of abdomen is to be done for approach in your case. If still no cause found and condition deteriorating endoscopy can be done. Avoid stress and take healthy nutritional diet with more water and fruit. I hope my suggestion will help you in diagnosis if your condition.