It could very well be a tonne of things; I'm assuming the vet was just listing a few of the wilder possibilities to point out that it could be lots. This is by no means a complete differential diagnoses list and there are more likely possibilities.

Dehydration is a good suspect. Are you using overhead heat, or undertank heating? Both work well, but I find that overhead heating really promotes a dry atmosphere. Many substrates also promote a very arid enclosure.

I think the big question is at this moment is if the vet did any diagnostic tests to get more information. Did they?

For the time being, definately review your husbandry to be certain it is not the problem.

Ian