PCOS and late pregnancy detection. This.

Hi sir/madam. My sister has a regular cycle of 30 - 33 days till march. She's regular until march. She engaged in a sexual activity on april around fertileperiod (No ejaculation and not sure of precum too). She missed her period which is due by april 26th. Did pregnancy tests on 3rd day of her missed period which came out negative. And repeated the test on 5th and 6th day of missed period. They both came out negative. But no signs of period and consulted gynaec. Did bhcg test which also came out negative. And also detected with PCOS earlier this month & doc gave tablets to get her period. We were relieved that she's not pregnant,but she googled something about PCOS and came to know that people with PCOS will take time to detect the pregnancy. She's having brown discharge since 2 days. Dont know thats because of tablet or related to pregnancy & now she's like freaking out. Iam trying my best to keep her calm. Help me with this. Thank you. 🙏