I have been feeling really good during this 2nd tri. I am 23 weeks and they last few weeks I just start shaking and dont know why. I am not cold. I feel fine. It just starts. It continues for like 5-10 min then goes away. It doesnt happen every day, about 2-3x a week. Most of the time I have to go lay down when it happens. Has this happened to anyone else? Do you know what this could be?