I have been vaping nasty China made juice. Only thing in town. Now good juice and throat closing., iam in the bathroom more then iam vaping. drinking so much water . I didn't vape much yesterday . but the day before I did. it was great just to get some good tasting juice and a even level of nic that was not making my head spin . had some candy yesterday hopefully it will get better good tobacco juice .
"Throat closing" could be allergic reaction. Some folks have problems with PG or VG. You could try 100% one then the other! see if the problem is less.
"High" nicotine varies a lot between folks. I was a 2 pack a day smoker, you'd think I'd vape at a fairly high level. I don't. 9mg on average. 12mg max. Some folks like "throat hit". I don't. Not even when I smoked. I preferred a "smooth" thing. You could try cutting your nic way down. See what that does.
Also, you didn't say if you switched recently. Often, quitting smoking causes a scratchy or even sore throat. That seems backwards but it happens to some no matter which method they use to quit.
Finally, it is always possible you're getting plain, old sick and it's coincidence. The vaping may have nothing to do with it. I dunno about your area but allergy season down here is pretty freaking bad lately. "Somebody just bury me already" bad.
Come to think, we lived a couple of years in MO a bit outside St. Louis when I was a kid. I remember having killer allergies there. Like a freaking flu or something...