Welcome and thanks for posting your query to HCM.
From your problem it appears that you are suffering from folliculitis
or we simply say pyoderma's of skin near genital area. It is a simple, treatable condition where due to blockage and infection of the hair glands at any hairy area of skin become inflamed, tender and pus filled. The possibility of folliculitis is high in individuals wearing tight clothes or due to continuous exposure of humid environment and so many of the reasons which are beyond the part of this discussion. Now the important part is- as these lumps are tender, itchy and painful so it is very much advised to meet a surgeon or gynecologist or dermatologist
who can prescribe you the most appropriate antibiotic to you. Do not forget to take complete course of treatment.
In between you can take pain killers round the clock or according to pain status. Sitz bath with (luke warm saline water in a water tub) 2-3 times a day will also prevent the further aggravation situation and will also help in drainage
of pus. Do not try to squeeze the area or try to express the pus by your self as it can cause spread of infection.
As per your history you had been sexually inactive for last one year and also the Test done by gynecologist supports the evidence that you are not having any Sexually transmitted disease
to be suspected. So the possibility of STD's is out in general.
Hope to give you the best of the information.
With best health wishes,
Dr Sanjay K Kanodia
MD ( Dermatology and STD/ Venereology)