Wow. I've had tooth aches before and I can't believe you've gone through this for so long.
Now if I have a toothache I don't even go to see my regular dentist. I head right for the specialist/root canal guy(s).
There is two of them and they are both interchangeable for the work they do. I call their office and I'm in a chair within the hour. Another hour later and I'm walking out the door pain free with one less root.