Мама двоих (3 года, 5 лет), ждёт третьего

Sharp, shooting back pain

I'm having sharp pains in my pelvis- toward the back to the left of my tail bone, I guess more towards my back. Sometimes they shoot down my left leg and really hurt! If I've been sitting in one positive for awhile it hurts to change positions. What is this?! A normal pregnancy ache? I never back pain with my first two babies.