I’m confused

Marlaina

I had a period from 11/12-11/20 and than it ended.. i had sex ( just got off nexplanon birth control on 11/16 in middle of my period) after my period ended I️ had sex every other day and my boyfriend came in me all times. Yesterday i had bleeding started off brown and pink and than light blood and it stopped today mid afternoon. What could this be??? I wasn’t suppose to start my period to December 11th. I’m confused.