Teenager. Severe Itchiness Around Vaginal Opening After Getting Oral Sex. No Help From Vagisil, Cranberry Juice. Guide

Hi, I am 18 and have never seen a gynocologist. I have only revieved oral sex once and shortly thereafter I developed an itchiness right around the opening of my vagina. I got some vagisil and applied it, but because it's external use only, it probably isn't going to help the intense itchiness right inside there. I tried drinking pure cranberry juice to lower the pH of my urine and still no relief. Should I see a gynocologist or wait to see if it clears up?
I am extremely nervous to have someone examine my vagina. I've never had anyone do that before except when I was very little am used to develope urinary tract infections. Now, my issue is mostly self consciousness, I'm not sure what to do!