Thank you for your query.
It is very unlikely that the "bumps" on the abdomen were due to chicken pox
as the lesions of chicken pox are usually more in the peripheries than on the abdomen or chest.
At times collection of sebum within the sebaceous glands (sebaceous cyst
) can be present on the scrotum
and it is usually painless unless infected.
Without an examination of the lesion it is not possible to give a definite reason for the "pimples" that you mention.
I hope I have answered your query to your satisfaction.
Wishing your son all the best.
Rajiv K Khandelwal