Yes, I have a horse that has happened to.
I am not at all up-to-speed on what conditions constitute nerve blocking but it does sound as if this particular vet is a bit excited to do nerve blocks.
Vets for all the very expensive knowlege they have, don't always have a 110%-spot-on answer. I have learned that throughout my life-long experience with horses. It's not their fault, sometimes they honestly can't see the "forest for the trees" because they have been taught to do things "this way" instead of think outside the box for horses with "outside the box" issues.
I learned that with my now 25 yo, diagnosed with EMS nearly seven years ago, and who might not be here today if I'd listened to the vet that diagnosed him.
I am also learning that with another metabolic horse who foundered, ended up with torn ligaments thanks a AFA certified farrier trimming him too short too fast. My leg specialist vet (whom I adore and have the very highest regard for) said this horse would now always have that "Chester" limp (think the old Gunsmoke series) because one tendon healed shorter than the other
Thanks to a wonderful wonderful member of this forum, SHE (yes testicles are not falling in good favor with me lately
gave me instructions for rasping this horse's hooves in-between Trimmer visits.
It's only been ten days since I started the procedure and my horse is barely gimping. His Chester Gimp is so far in the rear view mirror, I can't see it anymore. Even my non-horse husband is jaw-dropping astounded
My point to all that is, I really think you need to seek out a different vet, a chiropractor who does acupuncture, anyone with experience in dealing with your horse's particular issues, that can look at him thru new eyes and maybe see what's really wrong.
It could be, after all of this, your horse is being trimmed wrong by everyone that touches him. He may be that one horse in a thousand, like mine, that needs special trimming to support whatever issues might be inside the hoof and leg.
Whether his issues will keep him from a higher level of whatever your daughter wants to do with him, would still be up in the air, but if he'd make a great trail horse for her and a low level show horse, she would still have the horse she picked out and got attached to
I sure hope that all made sense. I know what I want to say but sometimes the fingers don't convey things quite right