Hi, iam getting decrease of my penis in size. And i am having masturbation habbit since 8 to 9 yrs. But I never get this problem.recently iam having this.and 1 more dought is iam having colour change in my penis as light brown colour. I used to do sex usually.but I use safety everytime. What is the cause for it.and iam very fearing of any hiv transmission chances. But I never do sex with out safety.please help me with positive answer.thank you.