Question plan b

Hi! I have a quick question. My period ended last week on sunday, and I took plan b last monday, the day after. Yesterday I woke up with to a period again only a week after! At first I thought it would be spotting, but it really is my period. I know plan b can make that happen, so I’m just wondering if this has happened to anyone else and if everything went back to normal after. I wasn’t supposed to get my period until June 13th 😩