That sounds like a pimple/boil, an infected duct. If it has whiteish pus inside then no doubt that is what it is. Most every man has a couple of whiteheads on their scrotum at any one time if they looked hard enough. They usually just go away, some opening to spill the pus before healing.
If this one is a bit large, greater than 1/4 inch and persistent then I would see a doctor.
Frankly I haven't been. I just assumed it was a razor bump or burn or ingrown hair or something. Don't know how long they normally last. But it's been awhile no spreading and frankly no other symptoms. I mean I say no itching but I mean, my balls itch since I was sexually active, nothing abnormal or extreme beyond that. Was just wondering if this was normal or should I even go see a doctor? Franlkly looks like a pimpil on my balls. Just one again, and that's it.
This will not be herpes, which simply does present like this, in that location alone or persist for an extended period.
What does your doctor suggest it is?