Hello,
At this age, it can be due to clogged pores or molluscum contagiosum. Molluscum presents as multiple, small, dome-shaped papules, often with a central depression or plug. Molluscum contagiosum is a common, benign, self limiting viral infection of the skin. It generally affects children.
I suggest you to get it examined from a dermatologist as it needs a physical evaluation and to confirm the diagnosis.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.