How do I help my niece? (I am her guardian.) She has recently been diagnosed with severe......read the rest!!!

...and permanent irritable bowel syndrome. This means that often she has diarrhea or constipation. She is eight years old so she is perfectly potty trained. When she is constipated, the doctor told me to help her by "forcing" her bowels to work WITHOUT LAXATIVES, MEDICINE, OR EXTRA FIBER, because her condition is not dietary. I have been told that this can be done by pushing on her feet or having her do her bowel movements in a hole, where she can squat. DOES THIS METHOD WORK??? How can I help her?