I have a gelding just starting out (one competition under his belt)

his dry work is fine can school with a low head but when he gets worked up up and tossing it goes. I dont have much control when he gets it up there. It's just started as the workload/pressure/speed has increased 

he is fancy broke with all his homework done

teeth and vet up to date

tie down? Bit change? 

thank you for your help 

Have you had him scoped post run? He may be bleeding 

When were his teeth done last?  Chiro? 

Ruling out any sort of soreness, I would try a Bonnet if it's just the head up and not nose out

I'm guessing hocks. If head goes up only in turns, a tie down would give him balance.