New to birth control pill

So I have a question, I stared my period January 13 and I just started birth control for the first time on the 14th. My period ended the 18th which is a few days shorter than normal. But since the 18th I’ve been spotting and once I think I’m done spotting it starts again. It’s not red tho is like a brownish sorry tmi. What should I do? Bad this happened to anyone? I’m thinking it’s because I’m not use to birth control but it alittle concerning.