Yes VET CHECK. Jester was stiff in his neck going to the left and it turned out he had a large bone spur in this left stifle causing him pain. Totally the other end of the horse, but stiffness anywhere is a sign of pain, especially if it's a recent development.
ONLY AFTER YOU HAVE RULED OUT PAIN: I would do a lot of loosening up and shoulder control. Haunch turns/spins, rollbacks, counter arc circles, making the horse really soften and bend. Also, make the first barrel his "resting spot." Work him at the gate, then run to the first barrel, stop at your rate point, let him stand and pet him, then walk a perfect circle around it and continue the pattern. Also do this at the end of your workout. Lope or trot to the first barrel, stop, get off, loosen your cinch, let him stand then head out.
It sounds like he is running up the fence too. Go ahead and go to the fence and do some rollbacks and really get after him, then go rest on the backside of the first barrel.
Do some all-left or all-right drills too to get control and make perfect circles. Then, do some spirals.
A video would help too. I'm just throwing stuff out there now.
Pssh.I didn't pick up the wrong lead
It's called a counter canter...
...A very advanced maneuver.