Thanks for the reply...
You're hitting on the same sort of possible causes I've been wondering about via my research -- I must not be crazy.
In regards to blood sugar... did have a bout where I felt high carbs were affecting my blood sugar negatively. (dizziness, tingling, dryness/thirst again) This was over the holidays and a temporary thing. Measured fasting blood sugar at the time and it was 99 and 100. Higher than should be, though, not necessarily diabetic. Had a post meal test of 114... Again in the spring, tested myself after a few deserts and easter meal... 92
I go about 160, 5-11, 26 year old... while I feel I did run into some issues with carbs, I'm not certain I want to say diabetes given my results. (though this was with an at home kit) However, seems high blood sugar can cause this sort of dryness. Though mine will be prolonged, and sometimes even when eating no carbs (virtually) for a few days.
I will say that there seems to be some connections to carbohydrates, though... in that dryness...burning eyes, dry throat... will become worse after, say, something like Pizza and pop. (pretty sure I've noticed this connection... but don't want to say that it is evident all the time, so have my doubts)
As mentioned before, have had a history of dryness/sinus issues before this latest, more severe and prolonged bout. And some of it that seemed to be very environment specific, at times.
This complicates matters. I started worrying about blood sugar, however, after that incident over the holidays... and haven't totally alleviated that concern despite glucose testing that didn't really seem to support diabetes.
Agree that the auto immune class of disorders seems to hold many of these symptoms. SJOGREN'S SYNDROME, in particular...though, I'm not exactly the average victim of this disease. Lupus as you mentioned...
I am a halfway frequent sufferer of mouth ulcers as well... I had forgotten to make note of. Currently have one that is coinciding with the dryness.
To perhaps backup the auto-immune angle, a bit... have had over the years at times the tendency to feel compelled to roll and crack joints. Not pain... but, a bit of stiffness? Though this doesn't seem to be as big an issue as it used to be.
Physically... feel pretty good in terms of energy, physical vitality. I guess I could feel a bit more energetic, but I don't feel heldback in this regard. Able to lift weights fine, run.... though, there are days with the dryness that I just feel lousier... and it becomes more of an effort.
Could be allergies or diabetes. Another thing it could be is an overactive immune system, which could include sarcoidsis, Lupus, MS, etc. I have the same dry issues as you. Vitamin B helps with the dryness in the mouth. Vitamin E oil helps with the dryness on the body. When the legs and feet get very dry or hands, A & D ointment for diaper rash helps. It stinks a little, but put it on at nighttime with a sock over it and your skin should be soft in the morning.