Pigmentation on nose... plz help me

Hi...
I am getting pigmentation on nose. As i am having fair complexion, it is appearing as a dark mark on my face.

One year back i took blackhead removal treatment in a parlor. From the next day my nose turned into dark color.

I met dermatologist once and she suggested that it is a pigmentation and coming due to exposed to sun long time. But I never exposed to sun long time.

I don't know what to do. It is so awkward on my face.

Plz help me..