What Causes Penis Foreskin White Dust With Stretch Marks?

Hello Doctor! I am a 22 year old male and i am virgin. For the last one month or so i observed that when i retract my penis skin backwards after a long day in the evening there is very minor amounts of white powder in between my skin and the head of my penis. And the latest thing i observed is just at the end of the swollen part of the penis(mushroom) there are minor stretch marks kind of thing. I wash my penis on a daily basis with soap(dove) and wipe it clean. And is the treatment costly? Please suggest.