I need your help ASAP I’m freaking out !!!!

So me and my bf went to Bangladesh for vacation and we had unprotected sex there and I took a “plan b” there. Everything was fine. I went back to the U.S. but he stayed. It’s been a few days since I’m back and I started bleeding from my vagina. I took the plan b on the 24th of April and I started bleeding on May 3rd. And I’m not supposed to get my period till the 17th of May. Why is this happening? This really sucks too cuz I don’t have anyone else to ask and my bf isn’t even here to figure this out with me. I’m all alone and I’m freaking out. Please help me girls.