I'm 17 years old and african american. I found a very small black dot on the bottom of my foot. I thought maybe I stepped in something but it didn't come off when I tried to wash it off. It's been there for about a week or 2. It isn't sore or lifted, and it doesn't feel any different than the rest of my foot. It's just this random black spot. Should I get it looked at by a doctor or is it going to go away on it's own and I shouldn't be worried?