Horrible back pain anyone?

Rachel
My back started to hurt at 12w and now I'm 14w2d and it's excruciating at times. It hurts on one side only, to the left of my tailbone, and it sends jolts of pain whenever I bend forward from the hips, lay on my back, or move my left leg (including walking). My uncle (who's a doc) said it sounds like SI joint pain. 
Anyone else had this? Did anything help? I may try swimming or yoga or physical therapy.