Hi,
I am a dentist and would like to address the issue of the sore tooth. It would appear that from what you have described, the tooth is abscessed and needs a root canal. Not seeing you in person or seeing your x-ray, I can make assumptions, but of course I don't know any of this for sure. The reason you have pain when a tooth needs root canal, is because there is infection in the bone around the root. The infection will show up on an x-ray as a dark area and the reason that it hurts so much is that any pressure on the tooth, will put pressure on the infection, causing pain in the bone and the ligaments surrounding the tooth. Corticosteroids or antibiotics will only make the tooth better for a short period of time and then the pain will come back.
Be assured that parking chewing tobacco will not cause a tooth to abscess. What you appear to be doing at this point is combining symptoms that you are having, together, and conjuring up in your mind that these are all related to your past history of using smokeless tobacco. Certainly, your first step is confirm that what I'm suggesting to you, is that in fact, you do have a tooth that needs root canl treatment. Next, you should see an ENT doc and get your throat checked out.
It's great that you stopped using tobacco such a long time ago. I hope that you find that your throat is OK and that the stress you are putting yourself through will be over shortly.
Please keep us informed as to what results you get.
Jerry