Welcome,
ECF really is a great site with knowledgeable people who are always willing to help. Consider lowering the amount of nicotine, and possibly the brand and flavor of the e-liquid. Dry hits (that awful burning taste) can cause a sore throat. Dripping sinuses may be a source of the problem, as well as a local bug that is going around. Some people have physical reactions when they quit smoking. It can last a couple of weeks to several months. Vaping takes moisture from your mouth. Be sure to drink lots of water. If you are not feeling well and the sore throat continues or worsens a trip to your doctor may be in order.
Glad you are here. I look forward to seeing you on other parts of the site.
~ Elaine