Spotting after sex

Hey everyone! Just a quick query. I was due my period around 25th of the month but did not appear. I had sex 27th Dec and had bright red blood right after but gone after I wiped. Sane thing happened around 3rd Jan but lasted until morning of 5th - bright red right after but then brown until it stopped. Just had sex tonight, the 6th and was brown blood after. Can anyone shed light?! TIA!