I have a gelding like this. I wrote a thread about it not long ago actually.
I’ve done ulcer treatment. I’ve done Vit E/Selenium. Never tried magnesium supplement but my gut says that isn’t his problem.
He has sensitive skin and he doesn’t love being fussed over. I’ve also come to conclusion this year that his experience being broke and handled as a young horse was probably very poor. He has a lot of anxiety over anything involving being tacked up. It took me a long time (and some videos by Warwick Schiller) to discover how anxious he really was because the signals were quite subtle. A lot of groundwork has helped that and grooming/tacking up is now more tolerable and pleasant for everyone. But he is obviously never going to be a horse that loves being groomed. I usually am a pretty lazy groomer but if I need to go a little more in depth, I provide him some alfalfa to keep him distracted.
I debated the saddle fit issue personally but I had saddle fit by professional and ordered for him. And he goes extremely well in saddle and put on significant muscle over his back since buying saddle so I’m pretty confident that is not his issue. Once I am on, he is ready to go to work and happy to do his job.
