Plan B Side Effects

So I had unprotected sex for the first time with this guy I’ve been talking to last week on Wednesday the 18th. The next day (Thursday the 19th) I took a Plan B pill just in case, and exactly one week later on Thursday the 26th, I started bleeding from what I thought was my period until I only bled for 2 days. I stopped bleeding today and I’m usually on my period for 5-7 days. Can this be from the pill and is this a normal side effect from the pill ? Has anyone else had similar experiences from the pill ?