What does Sciatica feel like?

Last night, I woke up in the middle of the night with extreme pain in my right leg. I couldn't stop moving to try and get it to go away. At first, I thought my calf was just cramping, but soon realized that my shin, ankle, top of my foot, knee, outer thigh, hip and lower back hurt soooo bad!! Achy, kind of burning sensation. It seemed like it was stemming from my lower back, but I couldn't find an exact point. Any ideas?? I'm 35.5 weeks - ftm.