ISO: Sourdough Bread Starter Problem

Hi, and help!

In my efforts to get a really pungent sourdough bread, I have started a new sourdough bread starter with plain, active-culture yogurt; sharp cheddar cheese for flavor; skimmed milk; whole-wheat flour; and have allowed the starter to sit outside in the forest for yeast introduction . . . Everything seems to be crusing along nicely in the usual manner and I am getting some great odors from the starter, but the hooch has a black or dark-gray tint. Research of numeous receipes, etc., has resulted in no mention of this phenomenon. Pink coloring indicates a disintegration of the milk, but I have no pink tint at all . . . just black.

Any experience or advice from out there? If I proceed and bake the bread, it certainly shouldn't kill my wife and me, because the life of all the flora/fauna in the bread will be terminated in the baking process . . . maybe just proceeding and testing the baked bread is the way to go, except none of us are intersted in dying!

Thanks for any help and advice!