I have a horse that carries his tail to the side when he travels in a circle to the left, but when he travels in a circle to the right he carries it normal. When working the patterns he tries to hollow out his back, put his nose in the air, and sling his butt when he turns to the left but when he turn to the right he can keep his head lower, rounds his back a little better and gets under himself better. What do you think would be causing this?