Bowel Problems (for a 20 month old)

My 20 month old son often has crying/screaming discomfort anywhere from 30 minutes to 1 1/2 hours before he has a bowel movement.  Then when he has a bowel movment it is very soft, not even formed.  It is so puzzling because it's apprx. 50% of the time before a bm not every time. We've tried going lactose free to see if that was a problem, but he still has episodes. He's had this problem since he was a newborn.  We're at a loss??? Help please!!

[mammo]

Take your son to see a Pediatric Gastroenterologist.  This is his specialty and can get right to the problem so your son can get some relief.  Take care.