Thanks for your query.
I fail to understand what you mean when you say the first labour was ' a back labour '.
Also, beyond 37 weeks it is common to feel backache
and pelvic pressure as your pelvis prepares for the imminent childbirth.
Normally, true labour pains are quite severe, associated with a hardening of the uterus
which you can touch, radiating to the back and groin, not relieved by medication or massage
Also they are associated with mucoid or blood tinged discharge and leaking of water.
However, since you cannot be sure, it would not harm to have a check up to know how far you are dilated.