Herbs that have mucilage in them would be worth looking into. Slippery Elm and Marshmallow are probably the best two I know of to look into. Mullein also has mucilage and is worth researching from what I recall. Mountain Rose Herbs
has supreme quality herbs that are fresh and effective.
Dr. Morse is a man worth learning from if you fully want to understand how to feel better by detoxing the body and allowing tissue regeneration to happen. You can find videos of him on youtube. I would suggest searching his channel for, ulcer, and see what you find. He has a lot of videos, but it is all essentially the same message, give the body the opportunity and it will regenerate and heal.
Fasting is an excellent way to regain your health. As the body cleans house during a fast it will also start repairing tissue. The Japanese cell biologist Yoshinori Ohsumi won the Nobel Prize for his research showing what happens to cells during a fast. You may want to ease into fasting though with an ulcer.
I think the smarter way to approach it would be to listen to Dr. Morse, eat fruit and herbs as suggested, then as you're feeling better you can begin fasting to really accelerate the healing. Avoid acidic fruits for now as well, lemons, limes, oranges, pineapple, etc. Stick to sub-acid fruit for a while such as mango, papaya, pear, peach, apricot, plum etc. The acid fruit will aggravate the ulcer, the sub-acid fruit will soothe it. Mango and papaya would be top choices for soothing the stomach and healing the ulcer.
You can also mono eat fruit meals, eating only one type of fruit for that meal/day/week, which would go a long way to sooth the GI tract, there is a man on youtube, The Mangotarian, who has videos of his experience eating only mangos for 6 months I think it was. I recall the day 80-something video was pretty good, with info about the process the body takes to heal.