This is all really interesting - one of the possibilities for gum problems can come about because of the hidden sugar in processed/cheap food. On Camino we tend to eat what we can get, without really concerning ourselves about provenance and ingredients - also, knocking back those ice cold fizzy drinks, and they are really full of sugar, and then, we have less opportunity for dental hygiene out there.
I am interested in the height thing - which is low barometric pressure of course (I have broken two barometers now, going over from France to Spain in a vehicle), and also interested in vitamin deficiencies - only having the face showing doesn't really allow the body to make Vit D from sunlight! - though, should we have a good diet at home it would take quite a while to appear ... I can see the crusty bread thing, but think (I may be wrong, I usually am) that there would need to be softness in the gums first, which would mean that there would be a problem already there ---- but this particular thing, of blisters at the back of the gums .. this is new to me ... I don't think I would like to lance those, nor try to fit Compeed or gaffer tape, so ....
on the whole I think I go with Wayfarer and the Jameson!!! as that will kill most bacteria if one swills it in the mouth for a while before swallowing - and will sneak a half bottle into my kit as suggested (hic)
or Veterano Brandy - if you do like shorts, or don't like them because they seem too searing, do try Veterano (a Spanish cheap brandy) as it is seriously smooth, non-searing, and delicious!
Thrush, though commonly a female problem, can cause red gums with small white raised spots but I don't think this is an issue here - I do so wish that I knew more (about most things actually).
One good tip is don't go to the dentist just before you go .. if they clean too hard, fit a filling not quite right, then it is you who will suffer - go a few weeks before you leave, allows time for things to settle down.