Bumps under arm
These bumps can be either a blocked up sweat gland in your armpit; these tend to be fairly small, around 1/4 inch.
Certain deodorants can irritate the pores and cause them to block up. If there are multiple larger lumps, you may have a condition called "hydradenitis suppurative" where the glands get recurrently swollen, tender, and often actually drain pus
. See an md. Treatment is controversial.