Period? Or something else?

Elizabeth • Momma to one angel baby 02.02.20 👼🏻 fur momma to four 🐶🐶🐱🐱💕

My S/O and I had sex Saturday evening and after, I went to the bathroom (like normal) and I put on a panty liner because I was wearing one of my favorite pairs of underwear and didn't want to get them gunky by chance. Anyway, I woke up Sunday morning and had started bleeding. I was really happy because I haven't had a period since September 1st of 2017 and my husband and I have been TTC for quite some time and I thought this might be our month! Well, early this morning, I noticed that the bleeding had stopped entirely. Not even any spotting. But all day Sunday I had a pretty normal looking flow with some small clots here and there when I would wipe. Everything seemed normal until this morning. Does anybody have any idea as to what could've caused This? I'm sorry for the long post. Thank you for reading though!