Cramping after he came in me

I'm guessing that this may just be a coincidence, but I figured I'd ask if anyone else has experienced this. 
I am on birth control and I never have a problem taking it daily. We typically wear condoms, only going without every once in a while. He's cum inside me with no condom a grand total of three times in our 5-year relationship (been on BC for each time). Last night was the third time it's ever happened and today I'm feeling crampy. 
My period is due in 10 days, though, and he was going really deep inside me last night. 
Has anyone ever experienced this before?
Just a note, this isn't a pregnancy scare post, though we are not currently ttc. 

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