Painful bump on head on the centre at the top. feels like a bump i'd get if i had hit my head, but i haven't had any injuries to it. what could it be?

Sebaceous cyst: A common cause would be a sebaceous cyst. They are full of a white cheesy material called sebum. They are easily removed in an office setting.

Scalp bump: People can get pimples, ingrown hairs, cysts, and other skin problems on the scalp. Since the scalp is tight against the skull, even a small lump will be tender. Avoid using any products on your hair except shampoo for now. If the tender lump is new, try a warm compress on it. If it does not improve after a day or so, see your doctor.

Benign tumor: Dear Rubes: Most likely it is a benign tumor of the scalp...The most common ones are a lipoma or a pillar cyst..Either one can readily be excised in an office setting.. Consult your favorite plastic surgeon..