Darkened skin on base of shaft?

I recently went to the doctor about certain symptoms, and he perscibed me Micatin 2%, and told me to apply it 4 times/day to the affected area. After leaving, i realized that i forgot to mention a symptom. At the base of my pens, on the shaft, there is a darkish spot, only like 1.5 shades darker than my other skin, and all of the hair in that spot is pitted, the follicles are inverted. After about 2 days of medicating 4 times every day, it hasnt changed... Ideas?