I used to have the same problem! My daughter is almost 4 and it hurt her so bad that she started to "hold it" which resulted in several doctor visits. After trying EVERYTHING, even prescribed laxatives, we tried MiraLAX. It worked great, and her doctor approved it! It is normally used for adults, but we just gave her about 1/3 of the regular dosage. It is a tasteless, white powder, and you can sprinkle it in anything....juice, milk, water, etc. It worked wonders, and now she never has a problem! Also, you can buy it anywhere and it is inexpensive.
at 4:18 PM on Mar. 26, 2009