My DD has the same problem. We are finally managing it now (2.5 months later) with a homeopathic remedy. I took her to the GP early on and got some Actilax and then Parachoc. All was ok with these (other than the fact that they were sugary gloop) but when I stopped using them she stopped going to the toilet. It got to the point for us where extra water, pureed prunes, prune juice, pears etc weren't having any effect. I then went to a homeopath for a consult and things have really improved and she now goes by herself without stool softeners. Don't leave it too long though, it just gets worse.