What to do if i have a painful canker sore in the back of my throat, what can be done?

If you can see it: And access it with a cotton swab, try a product called zilactin (many pharmacies carry). Place a small drop on the small swab and apply a thin coating over the canker (grab on to something- burns a little at first.... ) let your dentist treat it w other medications or a laser if you can. 10-14 days is the usual course for resolution. Good luck!