chronic loose stool allergy?

My little boy is now 13 months old.  He was breast fed for 11 and a half months and his stool was always very loose....but that didn't concern me or the pediatrician because it is normal for a breast fed baby to have loose stool.  

When I started the weaning process I started to introduce whole milk to him.  As soon as I started the whole milk he almost immediately developed a horrible bleeding diaper rash (he had never had diaper rash at all before this).  His stools didn't change any and his belly didn't seem bothered by the milk he just got a horrible rash.  

The pediatrician said it could be a form of a milk allergy and to put him on soy milk.  He has been on soy milk for  a month now and the rash is gone but his stools are still horribly loose.  In order to keep the stools from being completely liquid we have to feed him the BRATTY diet, and this only gets the stool to a "sludge" consistency not even anything remotely formed.  He probably has 4 or 5 dirty diapers a day.  I also give him a daily dose of probiotics.

I just feel like he can't live on the BRATTY diet, he is not going to get the variety of foods that a growing baby needs.  His appetite is good and he is on the smaller side but growing well.  The pediatrician just says keep doing what I am doing.  We have an appointment with a pediatric gastroenterologist next month.  Does anybody have any suggestions to help with the loose stool?

[Renee Radenberg]

His weight is between the 10-25th percentile and his height is on the 5th percentile for his age. He is still in the Growth chart which is good. Have you stopped all dairy products, yogurt, pudding, and cheeses, when you switched to soy milk? Suggest using soy yogurt, soy pudding, and soy cheese in place of dairy products. If you have stopped all dairy products, suggest going to Allergist to find out if he has an allergy.