Wagtail
Horse servant
My TB was very panicky about the saddle when we first got him home - he had a full on hissy fit when I tried a friends saddle on him for size and girthed it up, and then when when the saddler came out with some different saddles and my husband got on him. Rearing, bucking, twisting like a bronco, the works. Both times it was caused by touching him behind/underneath the cantle area. After I decided he was too dangerous to get on (I was pregnant at the time!) we arranged some physio sessions and he got a lot better. I agree with you about the memory of pain as he still has the odd 'hunchback' moment and still doesn't like being touched behind the saddle, but the reaction is not as extreme. Is there a specific area on your boy he's most sensitive to?
I hope it works out for you and your horse.
He isn't sensitive anywhere. Only when being clipped, but that is just around his gaskin and is normal sort of ticklish behaviour.