He sounds pretty fried jumping wise and those horses have lost any and all trust in people and what may lurk around the standards…like somebody with a pole or something that hurts on the top rail or repeatedly asked to go over bigger and wider fences then they can physically handle. They get taught to HATE and fear jumps because they suffer every time they are forced over them. Double that if they are packing an incompetent, intended or not abusive rider.
Once a horse gets scared and loses trust like that, it is very, very difficult to school it out and, unfortunately, it will sleep in the back of their minds and awaken unexpectedly often hurting somebody caught by surprise.
Unfortunately, have personally seen this several times in former GP level victims subjected to questionable training practicing and rough, if not downright abusive, riding who dropped to lesser levels when their brains fried. Despite many months to years of good handling and patient rehab, if they got anxious or scared, they could not cope. Period. They exploded. Typically around jumps but sometimes out of the blue, one I recall had been away from 4m jumping for 2 years and was routinely hacked out by a Pro trying to rehab it. He came back from a long hack one day and spooked at a wheelbarrow, flipped over. Put Pro in hospital. They sent him back to owners who retired horse from anything under saddle. Period. They had paid a small fortune fir him, vetted him to death, put 2 years non jump rehab into him but it was too little too late mentally. Thats what fried means. Happens in other disciplines too. Over face, over work, gimmick training, bad riding = scrambled brain,
Think jumps are out of the question for now. At least. IME horses that get fried usually have underlying health issues they were forced to work through or were drugged to mask symptoms while damage continued. Rearing is something that can hurt the horse as badly as the rider and the horse that resorts to it to avoid Jumping or any request doesn’t care if it kills itself to avoid it. Thats something to keep in mind,
One other thing, did you ultrasound or just x ray? Personally seen good horses suddenly start stopping, rear, spook for no apparent reason that never limped, blocked clean or no worse then intermittent 1/5 and had nothing of note on x rays. When finally sent to clinic for advanced ultra sound and imaging, rear suspensory damage was revealed…despite no visible signs or heat.
Not convinced this horse was not forced to work thru pain. Kind of the spice in the frying pan if you will.