Elizabeth
I feel so bad for you, my 16 year-old daughter suffers the same cankers as you do. This has been occuring regularly since childhood. I insisted and received a full work up for my daughter to rule out an autoimmune disorder.The blood work ruled out Bechet's Syndrome, lupus etc. it's not herpes and it's not an infection. Maybe that kind of investigation is what you need. We've tried expensive toothpastes, vitamin supplements- nothing works. The doctor prescribed full-strength lidocain rinse. It failed to ease the pain. Check with a rheumatologist, it might be helpful. Good luck. I'm praying for you. LL