You are spot on. He has a lot of hind end pain - hocks/stifles/suspensory. As for the collapsed frog, I don’t -think- so. He actually is wearing flat leather pads because the farrier said his “whole foot was a mess” and it would help support it. So, it’s possible that is part of the mess she alluded to.
I’m finding that. And it’s hard to find the good ones. I don’t know about you guys – but the best farriers are full up and not taking work.