Bless your heart, OP, I feel your frustration. Here are my suggestions and anecdotal reasoning:
Put shoes back on him. I swear, last week I did something to the ball of my right foot and it hurt so bad I was almost in tears every day by the end of work. When that pain resolved, my right calf muscle was in pain from walking weird while my foot hurt. Then my lower back was tight and sore due to the calf muscle hurting. I remember thinking, I will do whatever it takes if my horse starts being footsore to spare him this agony. I was tired, grumpy, and just not a happy human last week due to the pain.
Cut out the alfalfa. Iāve known a horse that 100% could NOT eat alfalfa, and Iām sure heās not the only one. This was a docile, angelic QH gelding that was used for beginner lessons for little kids. He was a saint. But feed him a pad of alfalfa and he became a jittery, glassy-eyed menace that overreacted to everything. I was told this about the horse, didnāt really believe he could ever be anything but sweet and gentle, and then saw it for myself when someone tried giving him some alfalfa. Totally changed his demeanor. Stopped feeding him alfalfa and he was immediately back to being his reliably sweet self. My own horse can handle small amounts of alfalfa (he gets it in alfalfa-timothy pellets, which is his āfeedā). But too much can make him a bit jittery too.
Put him back on Gastrogard. I never realized how ulcers could affect horses until I experienced first hand with my gelding the miracle of omeprazole. I never suspected ulcers with him because he lives the best type of life: 24/7 turnout, forage-based diet, fat and shiny. But when we moved to our current barn back in January, he became a lunatic. I posted here about it and someone mentioned ulcers. I started Ulcergard (full tube) and the change was immediate and drastic. Heās back to being a happy slugā¦his natural state, lol. Iām tapering down now and heās still cool as a cucumber.