Hi Sammy, I don't tolerate PG very well either, though for me it's chest pains and headache. I have gotten a little better over the few months I've been vaping though - initially I couldn't tolerate it at all, but now I can handle 10-20% in juice so long as I don't vape it all day. I did a kind of vaping equivalent of theallergy/sensitivity food challenges I've had to do before, with the purest PG I could find, and mixing it with plain VG (no flavourings or nic). The VG I vape I usually thin with 5-10% of distilled water or alcohol.
Since I'm an Aussie I don't have much to offer in terms of vendors, but wanted to make sure you're aware that often vendors use flavour concentrates that are PG based. I've asked vendors before if they can do 100% VG and they've said yes, but when I've if VG based concentrates are used, they've said no, that they're mostly PG based. When flavourings can commonly be around 20%, it matters!
cheers, and all the best to your girlfriend with it. I hope she can find a solution, like I have.