Snow fire ointment, I wear 2 pairs of socks, silk and wool over the top then neoprene wellies. Agree with vitamin deficiency being a factor mine improved when I started on prescription high dose Vitamin D and B12 injections. Hope you find something to help they are awful.
Sounds like they are running under BD rules without the pressure this may be helpful
https://files.britishdressage.co.uk/Tack-and-Equipment-Guide-2025-2.pdf
One of mine presented like this a few years ago, vet assumed allergic reaction a course of steroids sorted it and hasn’t occurred since, everything crossed for you
Following this after being put on the floor by my new boy….have had NH trainer out, thought we were sorted but did it at a venue, have booked another visit but hoping you will get some good advice. It’s a horrible feeling and mine is only 14.2 not 16.2
Wrist warmers really help keeping your hands warm, I have the Storm Chase ones also a fleece lined riding skirt, I hate being cold along with health issues that don’t help.