I have a little black bump on my head, about 3 mm in diameter. didn't always have it. what could it be?

Hard to guess: A dark brown or a black 3mm bump could be a mole. It would have to be looked at to see what it really is. One can start with her primary care provider, who can then refer to a Dermatologist if the bump looks suspicious or unusual. Warts usually are not that dark. Blackheads (closed comedones) usually are dark only in the center. A video consultation with our Concierge Dermatologists can help too.