I can't be certain what anything is over the internet, but it's probably Fordyce's spots and hair follicles. Fordyce's spots are harmless fat glands that are under the skin. They could be slightly yellow or whitish. Fordyce's spots aren't an STD or anything, they're completely natural and most guys have these on their penis shaft!
And hair follicles (probably the ones on your scrotum or ballsac) are just places that hairs develop and will soon grow out. Since you're in puberty, this is probably what they are.
You can also ask about these at your next check-up just to make sure they're ok - like I said, I can't really tell what they are except from the description you gave. Although I'm postitive they're not an STD
Hope this helped