Bleeding after period??

I always have a regular period every 28-31 days always loads of cramping the day my period arrives. Been ttc for over a year but recently found out my partners semen analysis contains no sperm so are currently waiting appointments so there’s no chance I could be pregnant.

I had my regular period on Tuesday 13th but with no cramps at all which is very abnormal for me. Am currently cycle day 12 and have started bleeding again but with no pain? Anyone any idea what could be happening?