This isn't a definite--but the condition PH-1 is worth researching. It usually affects children--although it might be affecting me/or has since I WAS a child. I wrote more on another thread. There's much more information showing up on PH-1 (et al) because of a new medication getting approved by the FDA in November 2020. The Mayo Clinic usually/always sees skin symptoms at a later point than I may be at--but online, I've seen others describe being older and healthier and having these skin symptoms. Wen something is Ultra-Rare, it can take a long time to get a handle on its full scope.
I'm still researching what's going on with me--so I don't even know for myself--but it might be worth investigating for your son. (More details given on the other thread.)
Your 9 year old may have milia. Lots of babies get this but it can happen at any age. https://www.mayoclinic.org/diseases-conditions/milia/symptoms-causes/syc-20375073 This is if the bumps are tiny. They are a keratin build up in the skin. If the bumps are larger, they may be molluscum contagiosum. That's a virus. Impetigo is something that also occurs especially around the mouth and nose but that is not visually as you describe. Based on your description, milia sounds the most likely. Can you take the child to a dermatologist?