Pic passing black yeast / mucus - cause for concern?

I've been passing lots of what I assume is candida for the past few months. I was using nystatin for a number of weeks which cleared out some shocking 'ropes' etc. I've recently added betaine hcl and judging by the real stress this has put on my liver and kidneys it seems to be contributing to a tonne more die off. I'm passing boatloads of yeast after enemas etc. the thing is, the yeast/mucus I'm passing now is a real dirty brown/black colour. This is not coloured by stool. Can anyone suggest what we might be looking at here? Is this simply the next stage of peeling the onion or is this cause for further concern?