Period being odd

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So I took plan B and then like a week and a bit later my period came one day early, and I also just started the birth control pill when my period started. My period is now on its 7th day when it usually lasts 5 days? Does anyone have a clue what’s up with that? Or is it just my body adjusting to all the changes? Idkkkkk haha in need of some help !! Thankyouuuu