Hi Dear, You seem to be right in your diagnosis.
Your descriptions points towards Bartholin's
abscess. Any infection in the perineal area may cause swelling of the lymph nodes in the femoral area.
This Bartholin's abscess usually is due to sexually transmitted infection - most commonly
gonorrhoea. During
menstruation, it ruptures and gets reinfected due to presence of menstrual blood. The correct treatment for this is control of infection by antibiotics, incision of abscess and marsupialization of the abscess edges.
The hardened red skin around the abscess is due to surrounding inflammation (
cellulitis). It will go with the antibiotics.
Considering the possibility of STI, please get your blood tested for VDRL also as
Syphilis is a known co-infection of Gonorrhoea.
Please report to your Gynaecologist without wasting time.