Implantation? Period? Help!!

Back story: been TTC for 3 months now. My period was 9/14-9/18. I started doing a ovulation test at 4 days after. No real difference in the test to make me believe I was ovulating (lines were the same one was a lil darker but not by much). Today I checked my CM and CP. After my CP There was a hint of pink and upon using a tissue and checking cm again it was still tinged with pink. My period isn't due til Oct 12. I'm usually like clockwork 28 day cycle. Think it may be implantation? Could my period be this early. My back hurts a lil but I think that's in my heard from thinking it may be my period. Also a typical period my thighs cramp really bad also and none of that today. TIA