Hello, So I Am 18 I Have Had 4 Sexual

hello, so i am 18 I have had 4 sexual partners, and Im not sure what is going on. My genital area is very itch and irritated. On my inner thighs I have small flaky raises, I have bumps lining my but, a cut a little above my anus, and when ever I scratch it this clumpy white/grey/black stuff is caked under my fingernails. What can I do to make all of this go away permenantly and prevent it from coming back.