Treatment For Painful Pimple On Buttocks

45 year old male with a history of melanoma 15 years ago. Have a painful pimple on my left front hip that I noticed turned black last night and was bleeding/draining. Gently squeezed it and this morning it is not painful but still is black. Can't get an appt with my dermatologist for a month. Does this sound like something I need to get treated immediately or can I wait a few days to see if I can wait the month?