period come back one week later?!?😪😱😡

Ok I'm just gonna describe what's happened Cos I need to know what's going on or if this has happened to someone else , so I started my period last Monday and came off the Friday as 5 days is normal for me. However after I came off I still felt cramps and sore boobs like I was still on my period and today(friday) I've come back on!! Why?!?? It's my birthday in 2 days and I was so happy that I was gonna be period free for it but now looks like that's not happening :( help