I have a mole (I am not sure if you can call it a mole) on my upper buttock. I have it from as long as i can remember. It looks odd. Its about the size of a pencil eraser. It has patches of black stuff on it with peel off sometimes. I went to a dermatologist once and he said it is a mole and not to fear about it. I get small acne on those patches rarely which ooze some puss and goes off later. From a week now there is a cluster formed there and it is sore. But it is bigger in size and not like the acne i used to get. Should i visit dermatologist again or do you think it is just the regular acne?