Wow, sounds like you definitely have sensitive skin then. Back in the days when I was at rock bottom, with rosacea eating away at my face, I used to apply straight oregano oil to my face in an effort to kill whatever was causing the rosacea. That didn't bother me at all.
With the tongue, I agree that a few applications followed by a long break is probably the best approach. It's been a few weeks since my first applications; I will probably do one every weeks here on out for maintenance. Good luck to you.