The first thought is that you have a yeast infection that is out of control. There are medications at the pharmacy for it, like monostat and vagisil. Read the instructions and do a double dose (6-10 days) if you see some improvement after the first round (3-5 days). If there is no improvement, see your gynecologist and be tested for otherdisorders as soon as possible. Good luck and good health.
Im not to sure but have you unprotected sex? maybe you have an STD.
if not then could it be dried cum or dried discharge?
maybeyou have dandruff...if its even possible to get it down there, it's best you go see a doctor to know forsure.