Have you actually used this starter? I would never use milk in any kind of sour dough starter. Not unless you want really nasty tasting bacteria in it. The usual sour dough starter is just flour and water. I have seen recipes that call for potato water, or the water you have left over when you boil potatos. I have a great starter for sour dough rye that is flat beer and rye flour. But I would never use nor recommend using milk.