It's like my skin is breaking up on the left elbow! And it get's kinda black?

I mean I live in a 1st world country and take care of my body but my skin on the left elbow looks dirty. I just got it away with using a lot of moisture cream (having it moistured 24/7) then I just could rub the black stuff off. But if it's not moist I can scrub with a brush for a long time and nothing goes away. (of the black stuff). It looks as if I had worn a black shirt for like half a year without bathing (which I didn't). But as I said. Using a cream that accerlates healing and is moist helps a bit. But it hurts. What do you think? Any tips or right to the dermatologist? Can anyone help? Please?

It's like my skin is breaking up on the left elbow! And it get's kinda black?
You should denfenitly see a doctor! why not? since cream doesn't help and it's alays like that, then maybe ot's on the inside. Good luck.