Don't know if you're still having this issue, but i registered because I feel sorry for you
I'm so glad you didn't believe that crook and get root canals. Your dentist sounds a bit weird too.
I don't have an answer for you as i just googled the same thing and found your thread, but i do have some theories. A crack in a tooth, spice getting under a crown, spice reaction with metals in a crown or filling, it's your gums being affected causing inflammation which makes your teeth hurt. Have you tried any natural non sensitive toothpaste? I use Jason Power smile. Might take a while getting use to because it doesn't foam as much as main stream toothpaste and isn't as flavorful (which I prefer). Just suggesting this because you mentioned using your toothpaste for a year and it doesn't sound like it's helping.
I hope your issue is long resolved. If it is, can you tell me what it was/what you did?