Period back to normal... Not!!

Hi ladies, I had my son on 13th December 2020, I had my first son in February 2019 and my periods got back to normal after 3/4 months, but this time around...

My sons almost 8 months and I've had only one period since I stopped bleeding after birth on June 13th for seven days. At the end of July I had one day of spotting and was like... Oh shit I'm pregnant... I wasn't 🤣 Fast forward to today I'm having very light spotting again but loads of cramping, I'd thought I'd thrown my back out from the pain.

At what point should I consider going to the doctor about this? I'm usually pretty much clockwork with a 31 day cycle and I'm not trying to get pregnant right now but I'm kind of worried that maybe something is wrong after this second baby. I'm only 24 so it's definitely not menopause or at least I should hope not!!!