OB or IB that's the question.

At 5 or 6dpo I have been experiencing light pinkish / brownish spotting mixed with cm. No panty liner needed, it lasted for 3 days. I don't know if it's Ovulation bleeding or implantation bleeding ( maybe none of the above). My period can be irregular so ovulation can be unpredictable at times hense the reason I am confused. If anyone has experienced this before I welcome any advice/ comments.