Lower back ache since giving birth 8 years ago as I had contractions in my back, how can I stop it hurting it shouldnt be hurting 8 years after?

You're right . Due to the changes that happen in pregnancy, your posture and spinal alignment can change. Sometimes, if that is not corrected, it can cause long lasting pain. I recommend the exercises that can be found in robin mckenzie's book, fix your own back. If that does not help, a good osteopathic medical doctor who specializes in gentle manipulation can help improve your spinal alignment and back pain.