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

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.