INPUT PLEASE

I AM 8DPO AND FOR THE PAST THREE DAYS I'VE BEEN CRAMPING LIKE AF WAS COMING ( PERIOD NOT DUE UNTIL THE SIXTEENTH). MY BOOBS ARE A LIL SORE NOT VERY MUCH, MY HEAD HURTS ON AND OFF, AND TODAY I AM CONSTIPATED, AND I THREW UP A LIL IN MY MOUTH. COULD I POSSIBLY BE EXPERIENCING IMPLANTATION OR IS IT JUST AF GETTING PREPARED TO SHOW UP? NEED SOME ADVICE OR SOMEONE WHO HAS BEEN THROUGH OR GOING THROUGH THE SAME THING. THANKS.