Missed period and fingering but no sex.

My friend is a virgin (she never had sex). Just sometimes fingered herself. She was involved in a sexual activity on 29th July. No penetration but her boyfriend fingered her. She and her boyfriend are confident that he didn't finger her using cum. Now her period is late. She had PCOS for which she was taking medicine but since the periods became regular since last 3-4 months, she left the medication. Second last period date: 28th May. Last period date: 3rd July. By now, she should have had her period but it's late. She did the kit test also using 2 strips in the afternoon on 12th August and resulted negative. And on 15th August she is having brown vaginal discharge and she is very stressed. There are no other pregnancy signs. What can be the possibility? What to do?