Any advice? Warning - TMI

I’m almost 5 months pp. been having regular periods for the first time in years. 2 years ago my smear test came back showing cancerous cells and tumour which was luckily benign and removed. Today whilst on the loo, something fell out into the toilet and it felt very strange. I couldn’t see in despite looking as I’m on my period. I don’t think it was a blood clot as it usually doesn’t feel like that and usually just when wiping. Any idea what this could have been? I had horrid pain prior to it happening but I sometimes get very painful periods although after that, the pain calmed. Should I get checked? I feel a little concerned?