Sayang, at 38w5d with back pain like that, please go to the hospital or labour ward sekarang juga , better safe than sorry, especially since you're third time mum and signals boleh berbeza. Back pain camni boleh jadi kontraksi atau just pregnancy aches, but doctors need to check proper-proper if baby ready or not lah. A few of my mum friends said labour pain feels different untuk setiap orang, so jangan rely on Google je, go get checked, okay?