Sudden severe back pain 38 weeks

Baby definitely dropped last night. This morning, I started to have sudden SEVERE lower back pain when I stand or walk, I mean 10/10 pain, with relief from sitting or laying. I have cramping but no full blown contractions. Does this sound like the start of labor or more like baby pressing on a spinal nerve? No other signs of labor, was 1 cm dilated a few days ago. I live 2 hours from my hospital so don’t really want to call my OB as she may assume it’s back labor and have me come in which may not result in active labor. I just don’t know! Anybody relate or have similar experience?