My first labour was LONG and very hard. Baby wasn't back to back but all the pain was in my back and never felt contractions in my tummy (retroverted uterus). So while labour number two might be different, it's likely the pain would be in my back again and I would expect it to be show (labour number one consisted of regular contractions for 72 hours, no sleep for that long and agonising unbearable pain).
Should I try a TENS next time?