Back and sides tightening up feeling?

38 weeks and I've had the contractions where my uterus gets super tight then releases and those didn't hurt now I'm having what feels exactly like contractions but actually a little more painful but I feel my uterus and it's soft which is weird and I also feel like my back and my sides get super tight like I get so heavy and it hurts and I'm so confused cause my uterus isn't getting tight but these contractions feel more intense and all over my entire body anyone else? Or know what that means?