My doctor said no to , but i'm still unsure? She said it was a yeast infection?

Okay so back in december I had with a boy and we used a condom. He went down on me orally and I didn't think anything of it at the time. It's now almost April and I finally got myself to ask my mom to take me to the gynecologist. When I got there, I told the doctor how I was scared I had contracted an STD and I'm not sure exactly what it is. For the last few weeks I've checked it out myself before the appt with the dr, and it was a small pimple sort of area not too far from my l area, but it wasn't too close. Also I'm always experiencing an itchy/burning/painful feeling when I wear tight jeans or if I sit in an uncomfortable position. And I've got a discharge build up. This is a constant feeling, not something that goes away and comes back. If it does go away, it'll come back after a week or so. When the doctor examined me, she said that it wasn't for sure but it was actually a yeast infection? AND when she was doing the examination she said there were very small raised bumps sort of near the l opening but they definitely were not . Is it possible that she can be right? Can it be any other STD or infection? Someone please help me, it is VERY stressful.