NOT MEDICAL ADVICE: It is most likely constipation caused by low fiber diet and/or inadequate fluid intake and exercise. Try increasing fruit and vegetable consumption-can't hurt!
The milk that your children drink could be one source of your children having painful bowel movements. We had this problem with my son. He was drinking whole vitamin d milk at the time. After switching him to 2% it got alot better.
Not drinking enough water is the cause a lot of the time. Others times it could be not eating enough fruits and vegetables and not getting all the necessary nutrients.
