What Causes Post Nasal Drip?

Had dental sugery a few months ago, had a wisdom tooth partially extracted, a root canal on the tooth next to it was told the adjacent tooth didn't need a root canal (lower jaw). I had crowns put on both of these molars. I had a lot of sensitivity on the tooth that the root canal was not done on, was told the sesitivity was due to my gums. I still have sensitivity with this tooth. As of a week ago I developed a pain alongside my neck with ear pain, I suffer from exaustion, I also have red teary eyes that sometimes twitch and either nose congestion or runnynose and I have a Post nasal drip. I think it is a dental problem what do you think? I scheduled a dental visit for this comming Wednesday.