You can develop all sorts of weird things when you are pregnant, lol. I had a numb area in the front of my ear (below the temple and above the jaw joint-- JUST right in front of the ear opening itself). It would drive me crazy. Because part of it was numb, the area right around the numb area would itch. It appeared a few months into my pregnancy, then went away after delivery. I had the same thing with a 2nd pregnancy. It went away also.
I had really really bad carpal tunnel with the first pregnancy (I couldn't grip a hairbrush or tooth brush for my teeth for half an hour after I got up in the mornings). I don't recall it being as severe with the 2nd pregnancy, but I was really careful not to put my hands under the pillow when I slept the 2nd time around.
I didn't have any weird stuff happen with my teeth/jaw during my pregnancies. But AFTER them I had some funky pains that went away over time without any treatment. It was almost like the swelling and extra blood in my body during pregnancy applied some pressure to areas and then when that pressure let up, there was extra space that exposed nerves or something. Over time things went back to normal.
I'd ask your doctor about it and see what they say. It might be a side effect they hear about often. Or it could be a symptom of something to watch. Or it could simply be what another poster mentioned : are you clenching your jaw or grinding your teeth during your sleep?