37+1 horrible menstrual like cramps😔

Last night I kept tossing and turning because my lower back was hurting and It felt like menstrual cramping through out the whole night. I was very uncomfortable. I woke up this morning and the pain was still there. Took a shower to see if that would make me feel better and it didn't. Soft stool and I'm just wondering if this could be the start to labor. Any advice or comments are appreciated. 37+1 weeks 2nd pregnancy.