Just recently my horse has been acting a bit weird when I ride him. He is grabbing the bit, sticking his head way in the air, and then running really fast. He'll do this suddenly, then come back and go normally for a while, and then he'll do it again. He also shakes his head periodically. He has never been super steady in the contact but this is above and beyond normal for him. I am not sure what to do or why he is doing this.