Sakit pinggang masa hamil memang very common, especially kalau duduk lama or posisi tidur tak proper! A few of us mums went through the same thing around week 13 onwards, mine got better once I started pakai pregnancy pillow and conscious about posture. Try to stretch gently, jangan stay dalam satu posisi lama-lama, and maybe ask your doctor about safe exercises or even physiotherapy sebab they can give you proper guidance. Sending you so much patience, I know it's uncomfortable!