I had 2 black spots/dots appear around the same time, one on the inside of my left thumb and the other on the back of my first right finger. They both disappeared around the same time, but I can't recall whether it was exactly the same time they both appeared and disappeared. They were there for about a month, (again, I could be wrong). Between I think a few weeks and a month went by and the black spot/dot reappeared on my finger, before disappearing. Neither were raised, had no other colour, were the same size, and perfectly round.