Lower back pain left side woman who carries heavy toddler around on same side hurts worse when first lay down?

Biomechanical: Carrying a heavy toddler will, of course, put a strain on the back muscles. The deep muscles of the back, along with quadratus lumborum may be involved. Start with yoga style stretching for the low back, also leg crosses and pulling kness to chest while lying on the floor. If your hips have rotated from repetitive strain, you may need to see a physical therapist for sacroiliac joint correction.

Many: This type of pain could be from lumbar strain, sacro-iliac joint dysfunction, arthritic pain or many other possibilities. There may be a simple treatment for you so see your health professional to get a physical exam and evaluation. I hope you feel better. Try carrying your toddler on opposite side if possible.