(Concern) Pelvic and lower back pain

Since I often bend my waist and hold the children while washing them in the bathtub, I have been experiencing pain in my upper buttocks and tailbone area as well as my lower back since last year. When I move without realizing it, my lower back hurts, and I instinctively lift it with my hand. What could help alleviate the lower back pain? It’s upsetting to feel pain in different parts of my body.