Dear Dentist

I'm serious pain as of tonight, my tooth I had a root canal done almost 7-8 months now that pain is back and I can't even open my mouth what should I do? the root canal was successful done now the pain is back, I have been smoking and taking antibotics as the sametime but everyone smokes, they never have any pain troubling them, a friend of mine smokes like 3 packs of cigrettes and never has trouble with his teeth and he's older than me he's almost 38 I'm 30 years old