Expelled blood clot. Was it a miscarriage?

So around the beginning of this month or last month, I don’t really remember when this happened, there was a huge blood clot that came out my vagina. So my bf and I just finished having sex, he came inside me. I went to the bathroom to clean myself up and pee. When I wiped there was a huge, dark red blood clot that showed up on the toilet paper. There was very minimal bleeding after that clot came out. I thought I was getting my period. I even asked my bf if there was blood on his dick, he said there wasn’t any blood.

Backstory, I remember having sharp, stabbing pains that would only last for a couple of mins and then I would be fine. I think my breasts felt kinda sore too.

Also, idk of this related to what happened but my periods were irregular. I would bleed brown blood for probably a couple of days to a week, leading to my period. So my period would last for like two weeks instead of one. That happened for a couple of months. My period started on the 17th and just finished my period yesterday. It was a pretty normal period, only last for a week.

So yeah that’s what happened. Idk if it was a miscarriage or my period.