what is this?

I had unprotected sex on 1st, 12th and 22nd. My husband didn't ejaculate in me, but had some pre ejaculate. On the 22nd I had a racing heart and random nausea and vomiting. The day after sex (23) I had some light brown spotting, a small bit of bleeding the next day (24) and brown spotting the next day (25). Then today (26) I had a gush of egg white cm. My cervix is high, soft and open. I'm just wondering what this might be. I have a 15 week old that I ebf. My periods have never been regular, but since having my son I seem to bleed about every 28 days or so and the 22nd would have been day 28. Did I only have a one day, barely anything period or is this something else?