I hate canker sores

Why do I hate canker sores?  First they are painful and mouth pain cannot be ignored.  Second, they are difficult to prevent and you just have to cope with them until they go away. And 3rd, we have no idea what causes them.  For a doctor, the 3rd reason is the most difficult to accept.  What the hell are canker sores?

The medical term is apthous ulcers and they are  round or oval painful ulcers