What Causes Lip Blackening With Greyish Patches?

i have a lip that is blacked out with a black ring patch by the side of my mouth and some whitish gray patches by the inner sides of my lips.this occured after the sides of my mouth got torn on both ends and i treated the sores with a pennicillin ointment.the sides of my mouth turned from white to red and then to black.i want to know what this could be.what infection am i suffering from?