Welcome to the world of sensitive teeth
. You have my sympathy. I'm not sure if my problem is like yours, but I have found that the only thing that works for me is toothpaste for sensitive teeth. Nothing else has helped and my dentists all have nothing to offer.
When the tooth dentin gets thinned, by brushing or gum recession, or perhaps periodontal disease, the nerve inside the tooth is exposed via tubules in the dentin.