L.B.
My daughter use to get them all too. I was afraid to change her diaper in public sometimes because it looked so bad. She isnt allergic to milk, or any food that I am aware of. Now that she is potty trained, she hasnt had them since. Once in a while my 23 month old gets one like it too. I know its not too much juice or fruit, because I only give them a recommended amount everyday (fruit is very expensive for us, so we use it sparingly). My doctor didnt worry about it, but if you are concerned, call yours.
Good Luck!