Implantation bleeding NO pic but maybe tmi

I'm on an average 36 day cycle and have been for about 6 years now. I'm currently at cycle day 27, AF is not due for just over a week. My fertile days were all last week and I bd'd every other day throughout. This morning I have got light cramps and brown smudges- mixed in creamy. I've put a tampon in just to be sure it's not AF- do you think it's implantation or start if af at an unusually early time for me- very unusually early. Never had ib with my other pregnancies that I recall. TIA 

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