When I first try e-juice, I feel sick and want to vomit, but just for a while, I get use to it, I use non nic juice as I am a non-smoker,If you have no other health issue, it is ok to try e-juice
Why??????????
Now to the OP. Mouth Ulcers are often a sign of allergic reaction. You can have an allergic reaction to the base liquid (PG/VG) OR the flavors/additional stuff in there. Mucous membranes (like that found in your mouth, throat) are highly sensitive....so it is absolutely possible you are allergice to either the flavors or the type of liquid being used. Sadly the only way to find this out is to try it. My wife for example cannot use backwoods brew tobac. flavs....she loves one of them, but it caused a similar reaction in her mouth/throat. She now, exclusively, uses Awesomevapors "desert tobacco". I try to get her to branch out as I'm the researcher of the pair. She likes the desert tobacco and sees no reason to try anything else. She's been vaping it exclusively for a cpl yrs (it was called Camel before).
Another noteworthy bit, if you can, avoid irritants in your mouth for a few days while the sores heal (Incl. smoking and vaping). then try a new flavor, in a new atty/carto/clearo (whichever u use). FWIW best OTC med for allergic reactions is Benedryl (diphenhydramine HCL). f/u with your physician. read the box, and do as it says.
I'm not saying you are 100% with out a doubt having an allergic reaction, as only your physician could venture to guess on that. But it is possible, and it would not be wise to keep on the same flavor/type while you wait and see if it's a "normal quitting smoking thing" or an "allergic reaction thing". Rule out the Allergic reaction by eliminating it from your "diet", allow yourself to heal, and try again.