Welcome to HCM,
You are probably suffering with Bartholin's Gland's Abscess
. It can be caused by a number of bacterias which include bacterial organism that cause sexually transmitted diseases such as chlamydia and gonorrhea
as well as bacteria commonly found in G.I.T. such as E.coli
. More than one type of organism might be involved. You should consult a Gynaecologist for examination & get Culture & Sensitivity of pus/discharge done for proper treatment.
Wish you good health,