Weird period clot?

S/O and I had unprotected sex on Sept 21st where he came inside me, I was due for my period on Sept 22nd so I honestly didn’t think anything would come of it. We’re “trying” in the sense of “if it happens it happens” but we don’t try every time we have sex and we don’t try on all the right days. So when my period didn’t come on Sunday I was a little confused and then today about halfway through the day today on Sept 25th I had light spotting and then about two hours later I had what I thought was just a very large clot but upon looking at it further it didn’t look like my normal clots and was much larger than my normal clots. Just wondering if this has ever happened to anyone else?! 😩