You need to give him time. Even if you were to sell him any other horse you get after him will also go thru this exact same phase. They all have their waves of being punks, all of them.
In his case it sounds like there is something bothering him and you need to figure out what it is. Selling him won't solve the issue.
Once you have ruled out his tack, taking some lessons with a professional would be I'm sure of great benefit. He/she might be able to help you figure out whats going on with him.
Bailing on him is the easy way out. Keep your chin up and try to see if you can understand what he's telling you.