Hi I Think I May Have A Std. I Was

Hi I think I may have a std. I was going pee and I noticed my privet was hurting me when I pee and when I wipe when I check my privet I noticed I had a open sore on my privet . Their was black stuff one looked like a big bug I thought nothing of it. Can you help me? My name is hannah and it's hard to say this to people but I can't wake up I wake up and I feel wraped is their some thing you can recamend for me? Possibly std and for brain function.