Ok I need some help with this. I just had sex for the second time ever and it was a little rough. We used a condom both times and lube this last time. But now on the inside of the lips of my vagina there is what look like a friction blister. And sometimes a little itchy when I go to the washroom. Is it a friction blister?? There’s no possible way it is an STI. Or is it possibly a yeast infection??