@Mareish I think I own your horse’s twin. My experience - sound shortly after shoeing is a clue and it has everything to do with breakover point. Not lame enough to even block but you could feel it a week or so after shoeing. Rads were clean, MRI showed very minor thickening of impair ligament, more consistent with chronic loading, no evidence of traumatic injury. Bar shoes didn’t help, and she hated any type of full pad, pour, anything that added frog pressure. Horse has tendency to grow more toe than heel. Both vet and farrier agreed that breakover point that existed when she was freshly shod was her foot’s happy place. In any kind of regular shoe we tried, as soon as her foot grew even a tiny amount, especially at the toe - it didn’t work for her, a minor change in breakover was enough to cause the problem. Basically the same diagnosis - no absolute findings on rads or MRI but consistent with caudal heel pain/navicular “syndrome”.
What worked - the Natural Balance shoes with rim pad and trimming her toe back. Loves them. But it was a bit of process. It took some time for her foot to settle down. First shoeing she got three weeks. Next shoeing almost made it to four weeks, etc. It may take a while for farrier to be able to get her trimmed to where heel/toe length work AND keep angles correct. Two other things helped once vet and farrier felt they had a good idea of what was going on. Decided to inject coffin joint even though that wasn’t the issue - the idea was more to bathe the joint and effuse the area to address possible residual inflammation since we’d been messing around with this for a while. Six weeks on Equioxx for same reason.
She’s been sound for over a year now. She grows a good amount of foot so we are diligent about keeping her on a 4.5 - 5 week shoeing cycle year round. If the ground is hard and for horse shows, she is perfectly happy to have he feet packed with the Magic Cushion/shavings concoction.
Best of luck. It might take some patience but the fact that she can be sound right after she’s shod is a good sign.