My daughter had that. Supposedly they do go away on their own over time...but not usually within 6 months. What I read (and was told) was UP TO 2 years. When they get inflamed/infected (usually by scratching) is when they can both clear up AND spread. So you have to be careful and keep them covered when they are irritated. Also, bathing can spread it (shower him instead) and don't re-use the towel. Wash it after one use, in hot water and vinegar or bleach.
When we went to the derm, we didn't get just acid. Our derm used a combination of prescription strength wart treament AND cantharadin (the bug juice stuff). She just put a tiny dot of it directly on the tip/top of the molluscom bump. Then a band-aid over the top. Directions were to remove the band aid in aprrox. 3 hours and wash with soap and water. That they would get inflamed and blister within a few days. (they did). The treatment is to irritate the bump, to initiate their bodies' natural immune response to foreign/invading bodies/substances. It worked. They blistered a bit, got yucky looking, then cleared up and went away. The whole process (after the treatment at the derm) took about 3-4 weeks. They say it can take up to 6 weeks, and that sometimes a 2nd treatment is needed. We didn't need it.
I also discovered that stressing over it can bring out more bumps. Be careful that you aren't stressing him out more over all this. I have read to make sure he is eating a well balanced diet that promotes healthy immune response. Normally, only folks with a weak immune system actually get these---even though it is very common in children to get them. Ummm probably because school aged kids are exposed to a constant stream of germs from their friends and their immune system is constantly in overdrive learning to deal with it all.
We tried the tea tree oil before going to the dermatologist. It didn't really do anything, except add stress trying to apply it without somehow cross contaminated some other part of the body.... we went through scads of Qtips. And it was a 30 minute ordeal after bathtime, trying to make sure they were all treated....because when you start getting paranoid about it, even KP (keratosis pilaris---clogged up hair follicles/pores--fake goose bumps) starts to look like "baby" molloscum.
Finally, I said enough, and took her to the derm. After that, we were good. Haven't seen anymore around here in a few years. Whew!