The lump you are mentioning can be due to folliculitis
followed by abscess
as you also give history of hair being pulled off.
Also it can be a bartholins abscess or cyst
which is also very painful and requires removal.
Both the condition i have mentioned are infective and need to be treated. It can also interfere with your delivery causing obstruction.
I suggest you visit your gynecologist at the earliest and get it managed.