I don’t know much about mouth ulcers. But breathing through your mouth can cause dry mouth. My dentist gave me some special mouthwash that keeps mouth … moist … and it helped other issues. 

 Do you know what that mouthwash is called? 

 No. I’m sorry 😢 I tried to remember but it’s been a long time since I used it. But he did have to give it to me. Couldn’t find it OTC back then. 

 Thanks. I guess I would have to ask my dentist anyway. Good to know something like that exists.