period??? Need Advice and Answers Please

Kourtney
Are you on your period if you have painful what feels like period cramps 
Even If there is no period blood yet? 
I'm supposed to be starting today 
but I'm only having painful period cramps but No period blood yet. 
I'm also on the implanon .
But my cramps have been really painful the last 2- 3 days even tho I'm not bleeding yet. 
I assume I'm not on my period if I'm not bleeding yet ,
 even tho I am having painful period cramps. 
I would really appreciate it if people comment and give me advice and answers