I suffer badly from boils in this particular place as I have hidrenatitis superativa (do NOT google if you are eating or easily grossed out)
Mag sulph is a good start, as is heat. If you're using mag sulph, leave it overnight then remove it. If it hasn't worked, to it again the next night. Don't have it on in the day as its a gritty paste and irritates easily
You do have my sympathies though, they're very painful there