What Causes Painful And Irregular Bowel Movements Along With Appetite Loss?

Hi, my daughter is have irregular motion and she strain her self when she passing stool. every month she suffers a lot and sometimes it will take more than 5 to 6 day to pass. at this time she do vomit and intake is reduced drastically and put her into illness completely. She is now 5 years. your advice is appreciated. thanks