Period WAY early

Tara • 02.22.16 ZJLA Baby #2 is on his way!!!!
3 weeks after my period I started spotting. Just once, maybe twice. Wednesday thru Friday. So I was hoping it was implantation bleeding. Well today (Saturday) I woke up with excruciating cramps and a little while later started my period. I wasn't suppose to start my period until Tuesday. 
​I'm just confused by all this. ?
​My last period was a 28 day cycle ?