Either he's overfaced or he's putting you on. You can check both with the same exercise. Setup up a baby jump or crossrail. Take him straight to it. If he sails over it with no issues, he's probably either lost confidence in the larger jumps or possibly having pain with the bigger jumping effort. If he still balks at the little crossrail, it's time to go back to basics. Make sure your driving him squarely to the fence and not giving him any escape route. If he does try to bail out, don't let him turn away from the jump. If you let him complete a circle, he has succeeded in turning away from the fence. Instead stop him, back him up, side pass, whatever manuever you need to get him back in front of the fence again. Then make him go over it, period. Keep doing it until he gets the idea that his new runout strategy isn't going to work. Good luck.