Experiences with implantation bleeding?

I am 10-11dpo today. I have a 13 day LP. With my two other kids I have never experienced IB. But yesterday morning after taking a FRER (bfn) I had a long strand of ewcm. I examined it, and noticed that it had a small inch or so long strand of red blood in it. Really small and if I had not checked, wouldn't have noticed it. I expected to start af early (which never happens. I also never spot) because after I saw that, I started having really bad af cramps. They were more localized in my lower back and sides and really intense. I never really cramp in my back with af. The rest of the day I just had more creamy/ew cm and two little pin tip sized dots of red blood when I used a baby wipe to check my cm early afternoon. Today I am cramping more in my back and have a very localized spot in my uterus that hurts occasionally. I am trying to hold off to use another FRER until tomorrow. With anyone who experienced IB, does this sound familiar to what you went through?