Hi I am a 21 year old male and about a month ago I have noticed a dark discoloration on my penile shaft. It is hard for me to tell if it has grown or remained the same in the past month but it is about 1 cm. It does not hurt in anyway and there are no other symptoms. I have not been sexually active through penetration but have been around the base. please let me know your thoughts on what I might be experiencing.