Well, I stopped smoking about a month before I began vaping. Could it take that long for the toxins to come out of the body? Also, I never considered the allergy idea. I did drink two redbulls while vaping today, after which, I began to notice the sores appear on my tongue. Could have something to do with energy drink ingredients mixed with my e-liquid. Not too sure. I'll have to look into this further. I have a heartburn problem with the vaping that can be tolerated and avoided with antacids, but tongue sores are going to get VERY annoying if I can't figure out how to prevent them. I can't stand ulcers. I do have a very sensitive mouth, so I figured it could just be me trying to get used to nicotine vapors. I'm very sensitive to salts and acids or any kind of sweets. Nicotine is strong in liquid form like that, so could that be what's causing irritation?