Hi, My Left Canine Tooth Has Been Bothering For Over

Hi, my left canine tooth has been bothering for over a year now. i have been to a dentist multiple times, but they have supposedly confirmed that my tooth is fine.
please help!! I dont drink very much pop (16oz per week) or eat candy. i do smoke cigarettes but i dont think that rots my tooth like this. please help me
the pain is bearable but my tooth's sensitivity is getting worse