Abdominal cramps. Return of the period?

iestrella

5 months postpartum and the past few days I've had this upset stomach. Not while I'm breastfeeding and it isn't food poisoning or diarrhea. I know the uterus contracts while breastfeeding but thought that feeling was done earlier. Feeling crampy and sometimes a little nauseated. Definitely not preggo. Anyone had a similar feeling when they're period came back?