Birth control question

Hey guys!

I started on birth control on July 17th, last time I had sex was the 27th, and then I got my period the next day on the 28th, when I was still on the pink hormone pills. My periods generally last 6-7 days, which means it ended between Sunday and Monday, but it’s not three days later and I’m still noticing dark brown spotting/discharge in my underwear. I usually don’t have any after my periods end, and I’m just wondering if anyone else has had something like this before?

Apparently spotting and random bleeding is common in the first while of using birth control, but I have been feeling mildly nauseous and sick on and off the past few days which is a bit concerning.

Any feedback is appreciated :)