Hi mama! Please check with your OB right away, lower back pain + puso pain + cervical opening at 35 weeks needs proper monitoring talaga, hindi dapat i-ignore kahit mild lang pakiramdam mo. I know it's scary as a first-time mom, pero better safe than sorry, at ang doctor lang ang makakasabi ng tama based sa full picture ng pregnancy mo. Keep me posted, okay? Praying for you and baby!