My PG sensitivity did not cause zits, although I wasn't vaping it long. Before going down the PEG400 road, you might try just the PG in flavoring (if I keep my PG under 10% I can tolerate it) the rest VG and 10% Distilled Water. It's actually a rather nice vape, it improved the flavor when I added the DW, which I was not expecting.
Just go back to the dermatologist, if your zits are that small, I'd think clindamycin cream and retin-A would do the trick. They are both topical.
Although, you could certainly TRY PEG400, I got mine (UPS grade) from Amazon and started with a small bottle, that I just mixed up.
If your zits are so puny, I don't get why ANYONE was offering you Accutane. That drug is ONLY on the market because TRUE CYSTIC acne can be so awful. I've seen pictures, and honestly, cystic acne is probably CAPABLE of ruining a person's life and/or building backbone. I guess you got an "aggressive" dermatologist. I wouldn't take it either, even though I've taken it before and done fine. It has been "suggested" occasionally, as a way to get my zits in full remission, but no thanks. I'd rather use retin A and not have any side effects, other than a need to use sunscreen which I would do anyway, living where I live.
Tell your dermatologist she doesn't need to eradicate every zit that has ever presented itself on any human. And, I'm glad that you are returning to vaping, rather than just going to smoking. Job well done, in my opinion.
Anna