Had unprotected sex, took plan b, now experiencing brown discharge like a period but just got off my period 2 weeks ago

Sooo long story short I was on my period, it ended then had unprotected sex but bought plan B the next day and now almost two weeks later I’m experiencing a brown discharge pretty heavily, almost like a period and an experiencing cramps as well. Was going to go to the dr but thought I’d look into it more first.