Neither seems likely
is very short acting - minutes...and leaves no residue
too does not seem likely causing a single symptom persisting like this.
It could be allergy - from medicines, infection and so on
See your dentist
again / if there is no obvious dental cause, see Ear Nose Throat specialist
In the mean time, there is one small suggestion! Just touch - for a few seconds - the the middle of your upper lip
, below the tip of the nose (philtrum). your sneezing will vanish, if you do in the beginning. Do as often as you like / as soon as you feel the need to sneeze - it will abort...
[This is not magic - it is a reflex inhibition and has scientific basis - it is commonly practised after eye surgery
to prevent sneezing causing increased eye pressure]
God bless you