fatigue and abdominal pain which was worrisome that she needed a CT scan is not consistent with constipation unless the child passes motion every couple of weeks , so miralax will not help if she doesn t have sever constipation . this abdominal pain which shifts the child away from school isn t consistent with functional abdominal pain either so it s must be investigated carefully . I recommend the following blood tests : -complete blood count and blood film -fasting blood sugar -urea and creatinine -thyroid function test - celiac screen : anti-TTG IGA and total serum IgA -urine culture. these tests are to role out malignancy , diabetes , chronic kidney disease, hypothyroidism , celiac disease and urinary tract infection which all can cause abdominal pain and fatigue . I hope this helps