Question- please help

Kelsea

I am on birth control pills. Last period was 9/4. I take my pills at night. Intercourse on 9/15 and early in the am on 9/16. I missed my pill that night (9/16 so it was AFTER intercourse) I carried on and everything has been fine. I didn’t “double up” or take the pill as soon as I remembered it, simply missed/skipped one dose. Today is 9/19 and I noticed brown discharge in my underwear. Is this from missing my pill?