Hi, my son also suffers from painful mouth cankers, he's had them for years. He has had blood work done, but nothing showed up that was unusual. The cankers are flaring up again, he gets so many of them, he has a hard time eating. His cankers just don't cover his mouth, but on his throat too and his face looks swollen. We tried all those mouth washes, baking soda, salt etc. they temporaily ease the pain, but not for long. They seem to last for a long time, poor guy. Going to try a allergist, and see if they can find anything. Hope to get him some help soon.
Thanks