If you've tried the natural ways to improve constipation, by giving her plenty of water, fiber in her diet, etc, and is not working, you should have your Ped. see her. One of my sons had constipations problems since he was an infant. I tried everything with no results. As the GI Doctor explained later, if the stool is too hard and the child hurts when trying to go,they will , very quickly develop fear to go, b/c it hurts, He told us that many times when it looks like they are trying to go really hard, is quite the opposite, they are trying to hold it, to avoid the pain. This may cause other problems down the road, with his ability to retain the stool(is kind of long but important story). So in our case, he prescribed MIRALAX, which is a powder you mix with water, milk, juice, etc, it doesn't have a taste or add texture, it is a stool softener, it doesn't cause dependency. All it does is soften the stool, making it easier for her to go, making the whole process painless. Talk to your Dr about Miralax (I sounded like the comercials:-) . It really was the only thing that worked with my son. If you need more info I'll be happy to tell you and if you need a good GI doctor I can refer you to as well.
Good luck with your little one!
A.