Advice: This could be a difficult thing to train out of him. & like others stated- dangerous. Since you can't afford a trainer, I would suggest (like was said) to look things up online on a trainers page. Sometimes they do have troubleshooting ideas, which your problem might be specified. What I said has worked for horses I've had, but every horse is different so keep an open mind. Maybe look for clinics in your area that you could go to/participate in.
Don't show fear to him, as sometimes that invourages such behavior, but make sure you do respect him & respect that until he stops this he could seriously injure you. I would start at step one & completely retrain your horse on ground manners. I've always been told that if the horse doesn't respect you, he'll never take the time to respect what you are training him or doing with him.
I hope it all works out for you! It can be frustrating when you want so much out of em, but keep a calm head & work in small steps. & STAY SAFE! :) Keep everyone posted!
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