leaping!

Question
i have a 12year old fizzy cob mare who i've had 9 years.  recently she has started leaping in the air then throwing her head down pulling me off balance and reins out my hands thenm bolting.  once i regain reins i can stop so its not so much stopping her galloping its stopping her leaping and pulling me off balance.  she is ridden in a snaffle at the moment.  she gets plenty of work but she's always been very keen on galloping and hates being behind other horses (she is worse with leaping if behind)

Answer
I would check the bit and make sure it is not too tight or pinching her.  If you try and ride her in a halter you may see this go away, then you would know it is the bit.  I don't like bits and think they cause too many problems and hurt the horse.  Check into get a bridle less bit and see if she gets better.  My guess is it is the bit or your hands are too hard.  

Rick