What Causes Dark Painful Blue/black Crust On Nose?

I keep getting a dark blue/black crust appearing at the sides of my nose, not at the bridge but beside my nostrils. If I peel it off it bleeds for a while before scabbing over and that will just go a dark blue again which is painful. I've tried various creams which sting badly when applied to the area but nothing has worked. I've tried face masks, pore stripes and I do wash my face daily so I don't think it's a problem with build up. I'm an 18 year old girl, I don't wear makeup or have any piercings.