I have been diagnosed with barodontalgia; a tooth that hurts only when flying. i had a root canal, but that didn't correct it. what do i do now?

Tough one: If it's an upper back tooth, problem may be sinus as opposed to tooth itself. Tooth root may be fractured. May have accessory canals. See an Endodontic Specialist with a CBCT, a Cone Beam Cat Scan, that can take a 360 degree look around the tooth.

Not that tooth: your tooth is now dead, so it isn't that tooth. see an oral surgeon and rule out any bone involvement

Further Evaluation: I would venture 2 guess that that tooth may not be the culprit. It's often very difficult for a patient to pinpoint the source of dental pain. Trying to determine specific tooth in an office setting when the pain is not present is often a problem. Your pain may be from other teeth, sinus, bruxism in flight, or referred pain from a distant source. Not an easy task in office; can't over internet.

Barodontalgia: If your pain is limited to that one tooth there still may be an infection remaining. If it happens on both sides or sometimes on the other side than it can be sinus related. Ask your ENT, but using a decongestant nasal spray before the flight and again during the flight may help (it helped my son). If you had recent dental work rule that out first with the dentist.

Endodontist: There still may be a problem with the tooth. See a root canal specialist for evaluation. If tooth is truly normal, take OTC pain meds during flight.