I had some pink CM on CD5 & CD6 of this cycle when I wiped, plus big blobs when straining to go to the loo.
I have no idea what it was as too early for ovulation or implantation bleeding, plus I've never had ovulation bleeding in my life before.
I did read that cervical fissures could be cause too if OH has been a bit too rough, so I think it could have been that for me. But I'm going to go to docs next week about it in any case as it was extremely abnormal for me. I will let you know what they say.