B.Iggle
                    
                    
                    
                    
                    
                    
                    
                        
                        
                        I suffered for 20 + years with the type of canker sores that you describe.  They were usually triggered by stress and illness.  I was able to do my job (pilot) and they were not contagious. My wife was never infected.  When I was relieved of my stressful job they all but disappeared.