Spotting 1 year PP

I haven’t gotten my cycle back since having my daughter last June. I’m currently working towards weaning her from breastfeeding, as she has been successfully eating solids for ~6+ months. On Monday, I was crampy and nauseous and thought I started my period, but it was brown/pink and didn’t last more than the afternoon. I have endometriosis, have previously experienced ovarian cysts, and I experienced infertility trying to conceive my daughter, so I’m pretty confused about one half day of cramps, nausea, and spotting around one year postpartum. Could it have been ovulation, a short period, or even implantation bleeding?? Have not been preventing, but haven’t had anything to go off of in terms of trying since I haven’t regained my cycle. Had (really good) sex 11 days ago, spotting was 7 days after 😬