What Causes Rashes On My Child's Vagina?

My 1 yr old gets eczema and she is allergic to dairy. I starred giving her dairy products again because I had read that some kids grow out of their allergies to dairy. She got her rashes again on her cheeks, back, belly, basically everywhere. She even got a rash right on top of her vagina and the bottom of her belly where her dipper starts. When I was bathing her I noticed she was scratching her vagina area. I tried to stop her when she would do it for the very reason that I didn't want her to cut herself. But sure enough she did. Realized this because when she peed she started screaming and grabbing her dipper. So I checked her and saw she was all scratched inside. (Well when you open the inner lips). What can I do so it doesn't burn her too bad when she pees and she doesn't get an infection? I put neosporine and Vaseline on it to create a barrier but I don't no if that's safe.