He sounds like he might have back problems, or is in pain. My friend's mare did the head thing and turns out she needed her teeth floated. I would have his back and head looked at, rule out pain before you go punishing him.
If it's not pain, do anything you can to get him going. Use spurs and carry a crop, but DON'T use either unless necessary and don't over use either. For the head thing, if its ABSOLUTELY not pain, you can use a stronger bit, or use one rein and jerk his head to one side. Pulling both reins against his head will only make him pull against it, and he'll win. If you pull his head to the side, you'll be bringing his head up and he won't be pulling against the bit. Even if you're trotting do this. Spin him a lot every time he does it (and make sure its energetic spinning, not lazy - use a crop on his butt and spurs to turn him faster if he's ignoring you) and don't let him stop without you telling him to. After you spin a few times, urge him forward into an energetic trot, if its not the right amount of energy and willingness you want, urge with your legs, if he doesnt wake up, click, then smack with the crop. Don't just hit automatically.
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