Bleeding 4 days after sex and still going….

So I had sex with a partner of mine (only being intimate with 1 person right now and previously it had been over a year without sex) unprotected on June 29 at around 10-11pm. I don’t recall the sex being overly rough or painful but the next day I had some light pink bleeding the first day but now it’s red like menstrual bleeding and i’m having cramps. Now it’s day 4 and it is seeming to intensify. The blood is not enough to fill up a pad/tampon multiple times a day like on my regular cycle, but it’s enough for one pad a day without overflowing (for reference). We have had sex a few times before but always with protection and it didn’t happen. What could be the cause of this?

This has happened once before over 5 years ago with a different partner and that was also unprotected. But I believed it to be my period? Is this a thing that unprotected sex can make your period come during or shortly after?

My period is typically regular and lasts about 5-7 days but oddly enough my last period (June 15) lasted a little over a week (about 8-9 days)

Please help, thanks!