Start of a Period or implantation

So i have pcos and irregular cycles but ive been in clomid this was my second cycle. Suppose to start my period on the 15th what glow say but never correct due to me not having normal cycles and im never early im always really late or have long cycles.... I feel a lil crampy but nothing like af coming I usually get bad cramps and back aches and my boobs get sore... I usually get a indication and i have nothing but mild cramps... But can anyone share there story or comment wat u think is goin on