Started bc 1 week before period

I started having sex with someone new. A week after the first time, I went to have sex with him again and started birth control that day. I should have got my period a week later but I never did and I think it's because I started the birth control at a weird moment in m cycle. I've been having odd discharge but it's nothing like pregnancy discharge I'm thinking maybe an sti or yeast infection that the ointments didn't clear. Help..