Honestly, the first thing I wondered was "Tooth or jaw problem" and that possibly you have a cavity in that area or an abscess or something, that is reacting unusually to the sweetness due to a problem. I've had that happen with sugary foods back when I had (easily porous and somewhat problematic to begin with) teeth...
One area can just get super sensitized.
If you have a cold, I wonder if some lymph nodes in your face might be swollen or irritated too? Hence leading to odd taste sensations? This is speculative as others have said, you may just well need a checkup with doctor/dentist.
If your coil looks caramelized, it could be your equipment. I know when I (briefly) tried a few drops of burgundy in my vape (this is not recommended, I now stick with water and maybe a drop or two of vodka if I so desire, but I usually don't) to dilute my vape, it caramelized instantly and then my vape began smelling of curry, it was time to wash tank thoroughly and change my coil, as there would be no getting rid of that smell/taste I could see. (Taste not so bad, smell, utterly horrific). It's not a new bottle of flavoring is it, perhaps it is slightly different even if the same brand/flavor, or it could just be a new coil that isn't great, and maybe vaping a little differently than you are used to?
Again, all speculation but I do hope you get it figured out. Since it's concentrated in ONE area of your mouth though, unless you inhale DIRECTLY into that area well, it's unlikely to me that the vape itself is to blame, but IDK.
Best of luck, and do see a doc/dentist if it continues and your experiments with your equipment bring you no joy.
Anna
