Periods are even more strange now after having a baby

I’ve struggled with pcos since I’ve started my periods. It took me 10 years to have a baby. I always thought my periods would be better after having a baby but they’re not and if anything, they’re worse?! The only positive is that my period is now 5 days on average and used to be 7 days previously. They’re painful though. I’m not due on until next week and the pain has already started. Is it hormonal changes?