The lower you go in nicotine the better it will be

BUT, with that said.. it can also be a number of things... the amount of PG in it can have a drying effect, some flavors are harder on the throat.. ect...
Have you tried other e-liquid from different vendors to see if there is a difference?
I started at 20 mg with various vendors... some burned the throat, some didn't. I am now on 10 mg from one vendor. Try to find those that have sample sizes or free samples for first time orders and experiment.
And, drink LOTS of fluids!!!!!!! Vaping will dry you out