Ay, I feel you mama! A few of us in my mum group experienced sharp back pain on one side during pregnancy, and honestly it's quite common, could be ligament stretching, the baby's position, or even how your body's shifting as you grow, pero better check with your OB to be sure kasi you're already 25 weeks and they can properly assess if it's nothing serious or if you need some adjustments. In the meantime, maybe try a maternity pillow between your knees when you sleep on your left (which you're already doing, good!), and one of my friends swears by prenatal massage or pelvic floor exercises, pero really, don't wait too long before mentioning it sa doctor mo sa next visit, okay?