Nausea before period?

According to glow, AF is due today. I have been irregular though since my period returned in July (breastfed exclusively until June and started weaning in June). First period was July 15-22 but super light- mostly spotting. Second was August 28-September 2 and was definitely heavier but only for a day. Glow has my next period due today. This would be similar to my cycles prior to getting pregnant with my daughter. This morning, I felt a heaviness in my lower stomach like my period would be coming or something (never remember having the feeling before but I’m guessing it may be my period about to start). But my stomach is upset like morning sickness. I took a test Sunday that was negative and same yesterday (I don’t want to be pregnant yet but I’ve been worried so I tested). No period yet and it would normally start in the early morning hours for me in the past. I just never felt this kind of nausea around my period. Do period symptoms change after having babies? I have 3 kids and never had this before? I’ve always gotten cramp and bloating but never nausea