It's more likely to be hidradenitis suppurativa which is actually even more gross than if it were warts as they're (often infected) cysts/boils. I was kind and linked to Wikipedia instead of one of the medical sites as the wiki doesn't show photos... It's surprisingly common and can affect anyone but one of the biggest known risk factors for developing it is obesity. NB. I'm not responsible for any vomiting that results from reading the wiki!