Implantation or AF

It has been over 9 years since I was pregnant last. My period is not due until 6/10 and twice today I have found a light brown stain on my pad and.mijor cramping right now. I am usually regular latly with AF. Even though my spotting is very little, could it be implantation? I have used opk'S this month and had 3 LH surges amd have no clue how many dpo i am. I am afraid it's AF coming to visit.