What can cause thigh irritation?

For the last few days I have been bothered by tiredness and thigh issues, At times there has been this itchiness between my scrotum and my thighs. I noticed my thighs, getting dark, its like a dirt or something, and its very itchy , and when you scrub them there's like white small particles, I'm just embarassed to talked it to my mother, I am trying to figure my own problems out.