I reccommend sensodyne!! My issues are unrelated to my PCS, but since starting sensodyne, I've had a huge reduction in nerve pain!! I know that's what it is, because if I switch to a regular toothpaste (forgot mine on an overnight and used my boyfriends) it was back the next day.

It's worth a shot. Also, if you are truly in that much pain and your dentist refuses a root canal, go to another dentist. That kind of pain is debilitating and most dentists will do whatever needs to be done to decrease pain.

Hope this helps!