Hey! So I've had my orchid for quite a few months now and it went through it's blooming period, which I think ended a little sooner than that of my other phals because it went through a lot of improper care at the grocery store where I purchased it. I caught sight of some worrying things on my orchid recently and I'm wondering if I can get some advice and on what to do with my plant, and if I should cut roots, repot, or take some other action.

That's the whole plant! Recently a leaf turned yellow and fell off, which is what prompted my investigation. Here are the problem areas I spotted: I'm not sure what to do about the fuzzy black stuff on the root to the right of the image?

I'm also not positive why around the base of plant the roots are so black and discolored. I thought inappropriate fertilizer might've been the culprit but now I'm not so sure. Apart from that center, those same roots also don't seem to be dying or turning brown. The plant is still giving off plenty of new roots and otherwise seems to be thriving, but I would hate to see it die because I left it to succumb to fungus or something.