allergic to cows milk and soya?

[bjl1981]

Hey, since I've been weaning my LO I've noticed that he was getting a rash on his face when I was giving him yogurt. It didn't seem to bother him, but I didn't want to keep giving it him if he had a reaction. I tried all types of yogurt and then thought I was being clever and bought him soya yogurt. Unfortunately it still gives him a rash
I give him butter on his toast, and have given him cheese on toast and its never given him the rash. I've also given him the Heinz Breakfast yogurt powder and that was fine too.I'm a little confused. Anyone had this?