Pleaseeeeee

So my bf and I had sex last week. He used condom since the beginning and am in the birth control pills for about one month.

This week I’ve been having a lot of cramps and headaches This morning my period came (am usually irregular) but in the afternoon It seems like I didnt have it, it just appears like a brown-black spot, it’s that normal?

Do I have to be nervous of something?

Please answer me cause am freaking out