Why do cyst keep coming back on my underarm?

Furuncles. Hidraadenitisis a deeper i flammation of sweat glands. Overweight and or diabetes can lead to s'more superficial recurrent info tion caused by staph and or strep. Antibiotics are needed based on sensitivity. Preventive measures for furuncles are antibacterial soap and oral vitamin c.
Hydradenitis. Thus may me a sign of a chronic suppurative process known as hydradenitis. It can be marked with intimating periods of inflammation and infection and often requires surgical excision and skin grafting to heal.
Hydradenitis. Frequent cysts under the arm can be hydradenitis, a chronic infection of the skin glands. Often they require surgery. You should see your doctor.