The only thing you can do is use the process of elimination; and this is the only think a doctor can recommend. Put yourself in our place - all we can see is a little sore. There is nothing written on the sore that says what it's from, and we have no magic crystal ball that will tell us. The doc can only advise that you cut back or try to eliminate possible causative agents - and you can do that yourself with zero co-pay. BTW, I have heard of folks that got mouth & lip sores when they started
vaping. Some get them intermittantly, some get them only with certain formulations (flavors, VG vs PG, etc.), and some get them with higher nic levels. Dr. G.