Sakit pinggang and left-side pain at 24 weeks is pretty common with pregnancy, but since you're having daily pain especially when bending, better check with your doctor to rule out anything else, sometimes it's just the weight shift and your body adjusting, but they need to confirm lah. A few of us mums swear by wearing a maternity support belt (really helps when you're chasing a toddler!), and honestly, try to squat instead of bending when you pick things up from the floor, I know easier said than done with a 4-year-old around, but it saves your back so much!