Personally I think too many people have attributed symptoms such as the OP's as being "allergic" to PG. You also have to realize that when you stop smoking analogs, your gums get a much greater blood flow than they are used to. Your gums will very likely be sore, as they aren't numbed as they have been for years. Your dry mouth is due to the fact that PG, and even VG will absorb the moisture there as you exhale. This is also likely the cause of the "itchy throat".
I found that while e-smoking I drink a great deal more water than usual to compensate, and after a while I stopped noticing it.
These slight reactions aren't an "allergy", I'm sure you'll know if it's an allergy lol.