Hallow Dear,
Your history suggests that your Bartholin's Gland is infected. 
Bartholin's Glands are present under the 
Labia majora - one on each side. When it gets infected it is called as Bartholinitis. Usually they get infected due to sexually transmitted infections like 
gonorrhoea and/or chlamydia. Soon they form abscess which needs to be incised for drainage and the edges have to be marsupialized (sutured to the outer skin). The wound is allowed to heal by secondary healing.
If untreated, the abscess appears to be subsided temporarily during 
menstruation. This happens because it gets burst during menstruation. Again it starts increasing in size due to pus collection. Hence, it does require 
surgical treatment once the abscess is formed. 
From your narration, it seems that your infection has not progressed to the abscess stage and is still in the 
cellulitis stage. May be, it can respond to the prompt antibiotics treatment. Please report to the Gynaecologist ASAP for diagnosis and timely treatment. 
Please get your blood examined for VDRL test since many a times gonorrhoea coexists with 
syphilis.  Also get your 
HIV test performed. 
Your sexual partner needs to be examined for Sexually Transmitted Infections and HIV. 
I hope this gives you the important message.