Good day i had to have my tooth repaired, whereby a root canal was necessary, however the dr that had assisted me with it put me through the most. now a year later, today my supposedly "dead" tooth is in so much pain. i need help please. thank you?

Tooth Pain: The nerve in that tooth was removed. You still have living tissues around that tooth that also have nerves (gingiva, bone,sinus,etc) which can cause pain. The tooth may be re-infected, it may be fractured, you may have sinusitis. Please see your dentist and have the tooth re-evaluated.

Root canal: Sounds as if the root canal is failing. May be from fracture, missed canal, many other reasons. Please see a root canal specialist, an Endodontist, for evaluation and recommendations.