Lower back pain!

I'm 21 weeks and 3 days. These past few days I've been having horrible back pain. More like in my tale bone. When I'm lying down if I try to turn the other direction, I get a sharp pain, or when I get up or even walk. It's only in one spot and mainly to the right side of my butt. I'm not sure what happened. I'm wondering if it's normal?  The only time it felt better was in the shower from the warm water.