Please help me, I don't know what's happening to my body (women preferred to answer)?

my is sore but I don't know why. I'm a virgin and I haven't been partaking in any ual activity. I'm on accutane, a drying medicine for acne and I'm wondering if maybe that's what's causing the irritation around my opeing and rectum. but also, I used a lufa in the girls' bathroom and I'm wondering if maybe I scrubbed to hard or contracted an STD (the lufa wasn't mine). is there any possible explanation for this? will it go away and should I buy some type of l cream?