Pregnancy 37 weeks, started hurting in the lower back and vulva area, like…

Pregnancy 37 weeks, started hurting in the lower back and vulva area, like from bruises. With walking and turns, I had an ultrasound of the Lona showed 1cm exactly, they said to do an X-ray next week and if it's more than 1mm, then this is a sign for KS. Has anyone encountered this? Everywhere they write that 1 cm is already a sign, especially if there are pains.