Thank you for your query.
The description provided by you suggests carbuncles developing at the buttocks. They are very painful and would require a course of antibiotic and incision and drainage
(instead of the pop that you do manually). It shall be better to get your son investigated to know the cause of the recurrence of the infection.
I hope I have answered your query to your satisfaction.
Wishing your son an early recovery.
Rajiv K Khandelwal