Hello dear,
Understand your concern.
Brown discharge after post unprotected sex is pretty common problem in girls.
brownish discharge is due to
1. VAGINAL WALL TRAUMA: it contain atrophied endothelial lining of vagina.
so little blood due to trauma mix with cervical mucus form it brownish color
It indicate disturbance in blood vessels integrity
Sexual intercourse precipitate microfissure and frets in vessels lead to bleeding.
It can be prevented by using lubrication during intercourse.
But if it is associated with pain indicate urethral dysfunction
2.
Precancerous condition in cervix: Atrophied cervix get easily damage due to trauma and produce pinkish blood due to mixed with cervical mucus
3. Endo metrial dysplasia
4. Cervical polyp
5. Ovarian cyst/PCOS
So it might be a trauma to vaginal wall without pain and foul smelling.
But if it will not respond you should consult with gynecologist to exclude precancerous condition and infection(STD:
bacterial vaginosis an chlymadia)
Do the following test:
1. PAP smear
2. Gram stain and Culture from discharge
4. PCR and nucleic acid amplification test
You should maintain hygiene and keep vaginal area dry.
wash by using warm water with added salt.
Wear loose cotton underwear.
Use safer sex practice
Hope this may help you
Wish you good health
Best regards
Dr. Sagar