Why do I suddenly have tooth sensitivity & what can I do about it?

Saying your tooth is sensitive is like saying your car won't run.  It's a generality that needs more information to give a proper diagnosis and treatment.Could be a cavity...A crack in the tooth....A leaking filling...A tooth that has an unhealthy, hypersensitive or dead nerve....Periodontal disease that has caused gum and bone recession, exposing the tooth roots.....And certainly, it could be "bite related", meaning something to do with your occlusion, possibly aggravated by "bruxing" (grinding your teeth, especially at night) or "clenching" (which can occur anytime during the day, but often more severe while sleeping).If the desensitivity medications your dentist has used, or prescribing you use, isn't working, then you should return to your dentist, or get an examination and opinion from an endodontist (root canal specialist).  This doesn't mean you would need a root canal, but endodontists are the dentists most qualified to diagnose tooth related pain...they are specialists!By the way, Advil is not going to "solve" issues of constant pain.  Also, constant use of pain medications could certainly cause other problems.  Oftentimes it treats the symptoms of pain, but does absolutely nothing to solve the etiology of the pain.  Get professional help, either back to your dentist, find another dentist, or preferably, go to an endodontist.

Here are the reasons why teeth can be sensitivepatient is a clincherpatient is tooth grinderpatient has cavitiesteeth have leaking fillingteeth have crackspatient has gum recessionspatient had a recent cleaning and all the tarter and plaque is removed and so teeth are now exposed to air , and environment .teeth have lost their protective enamel layer due o acid erosion in diet or medicationpatient is undergoing medical treatment that cause such issues.Not having x-rays and without an exam , it is impossible to pin point your issues. Do express your problem to your dentist, and perhaps get a second opinion.