Could just be light bh. I'm due tomorrow so I can't quite remember if they started off mild or not lol. If it's tightening, cramping, and uncomfortable more than like yes that's what it is
I have been feeling cramping and tightening so i wasn't sure but it didn't feel like flexing
To me personally it's like involuntarily flexing your abs with or without period cramping. I tell my friends "flex your abs, now imagine your not doing it that they're doing it in there own." Sometimes I feel cramping, other times just tightening.