I'm not sure if this is something I need to be concerned with as the symptom appeared so quickly, but I had a one-night stand last night and when I woke up five hours later there was a small bump on my scrotum. It's kind of flat with a dimple on top. It's no more sore than a pimple or an ingrown hair would be.
I used protection, but obviously my scrotum wasn't protected. I don't want to violate the TOS by posting a picture. I don't have insurance, so it's difficult to go see a medical provider, but if you think it could be serious I'll find a way.