Do you suffer from heartburn?
I have suffered from heartburn and canker sores (mouth ulcers) most of my adult life, at this point I live off of prilosec. I realized a while back that the only time I get mouth ulcers is when I forget to take the prilosec, or if my heartburn over powers the meds. It's only happened twice since I started vaping and I know, at least in my case, there is no correlation between the two.
As for vapors tongue, it's best to frequently change up your liquids, including liquids from different manufacturers. Spicy foods and certain beverages can help, lemonade and powerade work for me.
ps, I have found that gargling with hydrogen peroxide mixed with water really helps with the canker sores, especially if you catch them early.