Mine started after 3.5 weeks of birth, I thought why so fast, is it good? Couple of days it started again
It might be more bleeding from your uterus healing. I had a few days of heavier bleeding, then a little over a week of light bleeding at 7 weeks. Then no period until 7 months. I asked the doctor about bleeding at baby's 2 month, he said it was probably just a layer of the uterus healing or something like that. I was breastfeeding and not on birth control. I'm not sure if that makes any difference.
It can take a while for periods to come back to how they used to be. They might be a little a messed up for a few months