Sakit pinggang dalam early pregnancy memang common, especially sebab hormones dan weight changes lah, tapi 9 weeks still quite early so best to mention it to your doctor just to be safe, a few of my mum friends had the same worry and their gynae gave them the all-clear, tapi better confirm lah since setiap orang berbeza. For now, try take it easy, jangan angkat berat-berat, and good posture helps jugak! Congratulations on your first baby, mama!