We have done EVERYTHING we can think of to help Luna and the ulcers on her mouth. Our vet is convinced it is caused by an allergy, either food or airborne, not an autoimmune disease, though I have been giving her l-lysine as well. We have changed her food and I think we have tried 5 different protein sources. We have changed her cat litter. We have changed our cleaning products. She has had steroid shots to make the ulcer go away but the last two steroid shots have NOT made them go away. Can anyone offer any advice? Thanks in advance.