any ideas??

So I'm on the last day of ovulation and today I had light brown discharge and a little bit of light pink when I wipe since Wednesday(highest peak of ovulation) and now it's all gone and stopped. I'm 27 and have had my period since I was 12 and never had this happen before do it's new to me. any ideas why that happened?? I will add that yes I know you can get pregnant this way but we pulled out and finished with a condom on Wednesday morning and also on Sunday morning.