4 wks postpartum, not breastfeeding. after bleeding stopped 1.5 wk ago. now have cramps and brown blood. is this my period coming?

Possibly: Typically the first period when not breastfeeding is 6-8 weeks after delivery. However, some women do experience their first period sooner than that, even if the bleeding right after delivery continues for 2-3 weeks. This cramping and bleeding could be the start of your first period or simply your body's response to the shifting hormones after childbirth.