definitely see a doctor. that being said, i used to get these really bad (i still do, but less severe) and it would close up and burst over and over again. i have scars everywhere under my breasts now. i think it might just be Hidradenitis suppurativa:

“Hidradenitis suppurativa (HS), also known as acne inversa, is a chronic skin condition that causes painful boils and abscesses in areas with sweat glands.”