L.P.
I don't think it would be lactose intolerance if she is still doing it on soy milk, simply because it doesn't contain lactose. It must be something else, sometimes it is that they simply don't digest as well...some kids are just slower than others. Have they mentioned anything about using soy milk, but adding a little cereal to it...sometimes this thickens up the stool...and then just keep an eye on her, there may be some type of digestion problem there, or it may just be her system isn't quite ready for milk...which can be solved by adding the cereal...and within a couple of weeks/months..it will fix itself and you can stop the cereal.