If it is Molluscum Contagiosum don't just wait it out. That is stinky. We did and it spread and caused DD all sorts of discomfort, etc. We used Zymaderm and it worked on clearing it. DD got it from her BFF. Children can spread it to others. Google Zymaderm and go to the website, all the info on it and pics are there.
My daughter also had Molluscum Contagiosum. Her doctor said we could take her to a dermatologist and they would prick them with needles to pop. Knowing our daughter, that was NOT an option. We waited them out.
I think she started getting them on the insides of her thighs when she was 8 yo. and they disappeared on their own when she was 10. They never bothered her unless they got infected (a couple did once), and those were cleared up with an antibiotic.
I researched on the web about it, and discovered that some products advertised to clear it up work for some people and some for others, but nothing absolutely works for everyone.
They are ugly and they are contagious, but that never stopped my dd from swimming and wearing shorts in the summer. As a matter of fact, I think the sun exposure and swimming ultimately helped to dry them out.
Just make sure your son doesn't share a bathing or swimming towel with anyone else (although we weren't too adamant about this, even after we knew what it was, and no one else ever got it).
If it spreads to the face, then immediate medical attention is warranted as it can wreak havoc there. My daughter's case never went higher than her wrists. Like I said, we left hers alone, and they're gone now and you'd never know she had them - no scars.
If that is indeed what he has - it sounds like it, but you definitely need a dr's dx for it - relax, keep an eye on it, and know that it WILL go away eventually, even if it seems to take forever.
My mother, a nurse, saw it one day and absolutely freaked. She couldn't believe what I told her the dr. said and thought I should take dd to the dermatologist. She nagged at me FOREVER about it. She is definitely old school, believing that drugs can cure anything. Our ped. is wonderful. They take the conservative, natural approach whenever possible.
Good luck, and let us know what the dr. says.