STI ?!?

So I had unprotected sex on the 20th and 23rd of March, and on the 3rd of April. Starting Monday, April 8th, I noticed some itching down there but assumed it must just be a change in hormones (AF due Apr. 13) even though that's never been a symptom before. The itching has persisted over the last three days now, but it's pretty much the only symptom I'm having. There's no discharge, no bumps, no pain when urinating, no stinging/burning, no pelvic pain, NOTHING. Today I looked and the area is very red and seems a little swollen, and the ITCHING is starting to drive me insane. My first thought was that it's an STI 😩😭 I have a doctor appointment scheduled for tomorrow but just looking for input and ideas tonight.