My child had (still does) the same problem. It can sometimes start from a painful bowel movement and they start holding back (could be the "poo-poo" definition). We have been struggling with this for years now. The pediatric gastro doc had us first try Milk of Magnesia twice a day and a regular time for him to sit on the potty every day. But by the time we got referred to the gastro, our son's colon had "vaulted" - expanded in places where the stool was collecting. Then it was like placque build-up in an artery. More and more would collect and harden until only a little could get by, and usually it was liquidy because that's all that could make it past. We ended up having to be put on Miralax which gave him major diarhea, but the doc and all the info I could find said that constipation is dangerous - it can be toxic and hold and deliver poisons from the waste into your system. We have recently had a break-through. It seems that because we all eat "health food" - whole grains, organic produce, nuts, lean non-red meats, soy, no sugar, etc., that we were contributing to the constipation. The fibre was too high and dry for him to tolerate. I now give him softer foods. Moist pancakes for breakfast with regular syrup. I added individual packed peaches in light syrup for his lunches to add a little more sugar, which helps to move the bowels, believe it or not. And Nestle's Quik to mix and put the MOM in. It took about 2 weeks, but he is having softer movements and does not complain about pain any more. He never said it hurt when he was little, he was 6 before he told us that. However, if you don't get this straightened out, the colon will vault and he will lose control of his bowels and have soiling accidents at an age that will embarrass him. Please talk to your pediatrician and ask for a referral to a gastro doc. You will be glad you did. Best of luck to you!!!