I just got on a 15 year old Standardbred ex racer who has never been riden before. he is doing great for never having someone on his back before, but there are some things I am having trouble with. The biggest issue is the bit. He won't stop playing with it! I'm using a curve bit and his tongue is either over it or hanging out of his mouth. On top of that, he throws his head around every time i put pressure on the reins. Anything I can do?? would a hackamore be the best choice?