Hey, I actually got my md to check this out for me. It happened to me like for months after I quit smoking (maybe 4 months). They aren't sores, they are just ulcers, which can happen for a variety of reasons, but most likely it is the change in ph in your mouth. This can happen just as a symptom of quitting cigarettes, or from vaping, or a combination of the two.They are a little terrifying, but quite harmless. If they sting, just dab a numbing agent like something for tooth pain on it, and try to avoid too much sodium as this will irritate them. They will stop once your mouth adjusts. If it does get painful, and you want a medical opinion, a trip to the doctor would be a good choice, just for peace of mind.