Spotting mid cycle.

I had a mc on September 3rd. I was 9 weeks along. I’ve had 2 regular (i regularly have longer cycles... 1st cycle was 10-31 and 2nd cycle was December 18) on this last cycle i started spotting brown/pink on cd 20(last Saturday) I was excited bc it was 6 days after we bd on New Year’s <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">Eve</a>. Thinking for sure it was implantation bleeding. I’ve been taking tests every morning and evening. Nothing. I’m now cd 25 and still occasionally have some brown discharge. Not enough for a pad just when I wipe. I thought it could have been ovulation bleeding too. Here’s a pic of my lh tests. None have been positive but they seem all over the place. Any suggestions on what the spotting could be from or any insight from those who have had a similar situations.