What I'm hearing is a horse that's getting more calories, protein, alfalfa, whatever, than he needs and less exercise than than he needs. He sounds sort of wired. I'd cut him back to straight grass hay and the senior feed. If he's owned by a festival (?) they can afford mats for under the horses feed bowls to help with the sand problem.
He's walking ahead of you and head butting you? I don't care how "nervous" he is that is disrespectful! He might be less nervous and more secure with boundaries. If his previous owner was afraid of him, he may be used to running all over people. This needs to stop. It's sometimes amazing how horses can calm down when they know their limitations; when someone else is in charge. Horses are a lot like kids. They like knowing someone sets limits for them: it helps make their world predicatable. A nervous horse needs a predicatable world, it gives him less to worry about. So don't excuse his behavior because he's nervous. That's just another reason to make sure he behaves!