Why does my mare throw her head and Crow Hop!?

My mare is VERY hot! She is in love with speed! But... when I dont let her gallop (if I hold her in a lope/canter) she crow hops and throws her head!! She went to a bad trainer and started throwing her head, so we pulled her out and I had to start fresh. She had professional training for reining for 30 days when she was real young. She knows some leg cues. She never even started crow hopping until this spring!! She is 9, and I have started her on barrels and gaming, she turns good but tries to swing out wide coming back so I go to correct her and slow her down but then she rears and crow hops! I don't know what to do so please WHY does my mare Crow hop & throw her head!??