See the excellent psychopharmacology advice above.
Thyroid issues or meds also affect 'vaping symptoms', i.e. they are in fact thyroid or meds-related (Syntroid is well-known for this).
Another approach is to remove vaping materials from the equation by switching to a hypoallergenic refill (one that is unlikely to cause issues for anyone):
1. Buy some 'Glycerine, USP' at the pharmacy. If the first pharmacy you visit doesn't have a small bottle (100ml or so) with exactly this on the label, move on to the next one, and the next, until you find a bottle that says: Glycerine, USP.
2. Buy some Pure Peppermint Oil flavoring for baking. It must say on the label: pure peppermint oil, no additives or preservatives.
3. Get some distilled water. If you can't buy some, its easy to make: boil some tap water, and the water that drips off the pan lid is DW. Alternatively, scrape the ice off the inside of your freezer: this is DW. It's just pure water with no additions.
4. Take a 5ml e-liquid bottle and clean it out very well. Use vodka etc. Then finally rinse it out with a mix of glycerine and DW.
5. Take the cleaned 5ml bottle and pour in about 2 ml of glycerine. No need for accuracy, about two-thirds of the bottle is fine.
6. Now add distilled water equivalent to about 20% of that. Accuracy doesn't matter. You just need to make the liquid thinner, that is the only reason you're adding it. You add just enough to make the glycerine look like a PG liquid in terms of its viscosity (thickness). Tilt the bottle around to see how 'thick' the liquid looks. About 15% to 20% added DW should do it.
7. Now add 4 drops of peppermint oil.
(Note that this is not an oil, that's just the term used in the flavoring industry, I vaped large quantities of this for nearly a year with no effect and have super-sensitive lungs).
You can also add a little caramel flavor from the baking flavor department, if necessary.
Now you have a 100% VG zero-nicotine refill liquid.
Virtually anyone can vape this without any reactions, there is nothing in it to cause any problems. The exception is an emphysema patient (lungs severely compromised by smoking), I'd advise some PG in it for that specific case.
The next step, when you have found that it causes no issues, is to add a little nicotine (and it must come in a VG base), if you need it. Buy 48mg to 100mg strength nicotine in glycerine (not PG), and add a tiny amount as needed. Take precautions when handling nicotine base (gloves, apron, paper towel at hand, open window nearby).
