Hi. Thanks for your query. Noted the history about your 8 years old sister and understood the concerns. Intermittent pain, constipation alternate with loose stool and being diagnosed with an intestinal infection last month indicate that the infection has wither reoccurred or was not cured fully. I would advise her the following: Get an opinion of a Pediatrician for clinical examination. Investigations of stool, blood and urine. Ultrasonography of abdomen to see for any inflamed lymph nodes, appendicitis or Meckel s diverticulum CT scan if required. X-ray of the abdomen in standing position. All these things will give an appropriate diagnosis to be treated according to the findings.