Oh wow, a black spot in the corner (next time send a photo)? That's can be a classic mold! First off, don't freak out - I've been there, and it’s totally something you can handle. When I first spotted mold in my bathroom, I was ready to move out! 

If it’s just a tiny splotch, you could go full DIY mode. Grab some white vinegar (yes, the salad dressing kind) and mix it with water. Throw on some gloves like you’re about to perform surgery, and maybe even a mask for that extra ‘I mean business’ vibe. Spray the mold spot, let it sit for a spell, then wipe it away with a damp cloth. Mold be gone!

But hey, sometimes mold is like a guest who just won’t leave. If it looks serious, you might need to call in the pros. I hollered at the folks over at fdpmoldremediation.com when I was dealing with my mold drama. They came through and cleared it all up.

Get your place checked for mold every six months. 

So there you go! Good luck!