How about a two step process. Day 1 take horse to saddlers where hopefully they have a warehouse of second hand saddles to try on him.
Try on lots of saddles.
Eliminate to best 5-10 saddles, that look to fit and be right size and style for you.
Day 2 saddler brings these to you to ride in and...
Sorry think I abbreviated badly. I’m aware bone scan mainly shows you were to look further. But my understanding is whilst won’t show you anything specific re soft tissue injury would normally show increased uptake in the surrounding area, giving you and indication there is something there...
Alternately, and speaking as an allergic asthmatic, if you cant breath well, you will be very docile. Maybe fixing the breathing issue has allowed the true forward thinking joggy nature to surface? Maybe he never was truly quiet? Just speculating.
I think you need to book him in for a lameness assessment. A place at a really good referral place of your choice, with a good expert, in holiday season might take a 2-4 weeks to book.
I'd get saddles both checked in mean time, if can.
I'd work him every day for 7 days before the lameness...
I paid about 600 for strangles blood test which was just above acceptable then guttural pouch wash to get samples to run at vet hospital to see if carrier. Wasn’t a carrier.
I could have waited and re run low bloods but clear result needed to move yards pre my surgery.
Spoken to farrier who thinks new type shoes behind next week and pads. He thinks he wants to land to outside edge of foot. Current shoes stop this but create jar. It isn't that visible within balance x-rays as he's rebalanced and shod frequently, so doesn't go that far out of balance.
There isn't a clear pattern of getting worse just after shod, or worse when due to be shod. It doesn't look like any connected pattern. Though I don't have absolute record of how he went, and remember this significant highs and lows, and the diary events / lessons / competing etc. is documented.