Almost everyone has had a mouth ulcer at some point. That small, painful spot on the inside of your cheek or along your gum that makes eating, drinking, and even talking feel like a chore. Most of the time, it shows up without warning, lingers for a few days, and eventually goes away on its own. Cold sores are just as common, though they tend to appear on or around the lips rather than inside the mouth. They look different, they feel different, and they are caused by somethin