2nd period after plan b 🧐🧐

I took plan b after me and my boyfriend had sex a day after and I had just gotten off my period when I had sex... about a day after I started my period again but the blood was brown and lasted for a full cycle (5 long days). I was very regular and got my period every 16th of every month and now I start every 24th. Me and my boyfriend plan on having sex again and I’m curious if that will happen again or change my cycle or keep it the same.. note today is the 23rd.. tell me if that has ever happened to you or just me.. 🧐😂