I just dont know where to go from here??
I'd say straight to the vet's office.
He is young, and you'd reasonably assume that he just needs an attitude adjustment. But before going that route, you should rule out any pain.
Once you've ruled out pain or injury (teeth, back, legs, feet, saddle fit), then it's time to look at you.
We're still giving him the benefit of the doubt.
So, have someone video you riding him in and out of the arena. Video those times that you are just relaxing and letting him walk in and out with no work and video when you are trying to take him in for an exhibition. You may be geeking up and scaring him . . . by tensing up, picking up on your reins, the way you are sitting in your saddle, you may be cueing him to be frightened. Watch the videos yourself, but also have someone else watch them. Heck post them here!
If you rule out you cueing him to do it . . . and you've ruled out pain . . . he just needs an attitude adjustment.
He has figured out how to get out of work.
That would be the time to start taking him into the arena, preparing like you are going to run . . . but then allowing him to just lope big circles around the barrels and relax.
If he rears up in the alleyway, untrack him. Put his mind on moving his feet. Can't get him to move straight up through the alleyway, turn tight correct circles . . . Side pass . . . back up . . . lope circles and then head him back up in there . .. every time he refuses he works - hard. When he goes in, he relaxes. Take him to the first barrel, stop him at the rate point and unsaddle him. From that point on only unsaddle him within the pattern, even if you didn't work the pattern that day. Take him around the first and stop him at the second, loosen him up and walk him out of the arena.