I have noticed that the end 3/4th of my penis shaft is very dark (much darker than my body) and the first 1/4th area starting from base is lighter, My scrotum is pink, and the underside of my penis shaft is lighter than the top half. So I have multiple shades on my penis itself. I am very desperate to lighten this or get an even skin tone. Please help. I do not have any STDs or other disease - as per my last checkup a month ago.