Well, some people do go through more psychological torture than physical torture when quitting smoking.
IF you see these other specialists and they find nothing wrong, a psychiatric referral might not go amiss. I'm not suggesting meds or anything else, but UNLESS something medical is found, some counseling and support while transitioning from smoking to vaping might not go amiss. Quitting is really hard. REALLY hard. I had a lot of anxiety during the process and felt fortunate that my smoking habit left me near death/feeling like death, so some stuff I was able to just ignore, since I didn't care that much if I lived or died, frankly.
With that said, DURING the transition process I DID run into issues, like nicotine overload, the wrong setup (for me) and a PG sensitivity.
So, it could be anxiety, underlying health issues generally, a psychological thing, or a need to amend your vaping technique/habits somehow, or a need for more real life support.
Start with the health stuff first, smoke if you want to (although personally, I do think that's less helpful if you do JUST have a medical issue.. If I was hospitalized for heart problems, I wouldn't be smoking, let me put it that way. But, do what you must, it doesn't sound like you are at risk from dropping dead immediately, but if you get palpitations after smoking, do call an ambulance.
Once all the specialists weigh in, if they come up "empty" as it were, a determined attempt to return to vaping (with help for the anxiety/whatever) might not be amiss. And you could still be sensitive to a vape ingredient.
But, you're going to have to approach it methodically and calmly if you want success. I would ask your PCP now for a referral to psych, if you do plan to continue vaping. It just would be useful.
Just my thoughts, as always.
Anna