thanks for the query.
If the lumps are on the outer skin it might be boils(furuncles
). You have mentioned that it is on and off. Boils are usually painful and might have a pus pointing center. Are you in the habit of shaving your armpit? that might be a trigger for boils. There is a condition called hidradenitis suppurativa
where recurrent boils
can occur in the armpit. A dermatologist
will be able to diagnose it.
Hope this helped, take care.