Hay hay hay hay hay. So many issues can be solved by more/better hay. you have an ulcery/ulcer-prone horse. That means you need to keep that belly at least partly full as much as you can.
Solo turn out with a slow feed net, or buy hay nets for all her buddies. I feed on the ground 24/7 with 4 one-inch hole hay nets for 2 horses, 6 when I had 3. More than enough ‘piles’ for everyone to be able to eat, and it stretches out the hay for longer, so you don’t end up overfeeding to try to keep hay in front of them always. My hay is pretty rich and alfalfa heavy for 2 of the 3 I had on it, so if I fed free choice I would waste a lot and have bowling ball shaped ponies. The nets are great, I have pretty heavy duty ones and the horses kick them around and they have held up well.
If you can’t keep hay in front of her where she is, move. You’re going to be fighting a never ending battle against ulcers if you can’t keep her guts working with hay the way they’re meant to.
If she’s still cranky after solving the hay problem, I have had great success with my cranky chestnut mare with raspberry leaves (Mare magic is sold by smartpak), and I also added epsom salts as a magnesium supplement, which seemed to make her happier as well.