HELP! What is this?!

So I’m due for AF in 5 days. Not entirely sure what DPO I am, but I believe I peaked 2-16 and ovulated 2-18. Took a test this morning and BFN. I had some dull cramping and left side ovary pain as well. Also a decent amount of thick white CM. So my hubby and I just did the deed (pretty normal, nothing new and not rough). I went to the bathroom and saw this. Any idea what might have caused this? Implantation bleeding can’t happen from sex right? Just curious!