For a year or more I've had a red spot on my back. It comes to a head, bleeds, dries up for a whole and then comes to a head again. The whole cycle takes about a month - I call it my 'period spot'. Showed it to my GP who dismissed it lightly saying it's just acne. But there is never any pus, just fresh red blood and it's always the same spot.
Should I be concerned?