There are many effective ways to control pain in Dentistry. RCT for most parts is a painless procedure barring some scenarios where pain may occur which too can be controlled with analgesics. Extraction is not the right treatment. I understand you are in pain. Get the RCT done from any good dentist your locality. You will fine. Don't get frightened and rest your worries.

Pain for root canal treatment does not occur when local anesthesia is effective..After proper cleaning of root canals i.e BMP( biomechanical preparation) pain gets subsided..To diagnose accurately whether RCT is the right procedure for you an x ray of that molar tooth is required..No need to get tooth extracted if it can be saved after the treatment..Visit a dentist to get it examined properly to proceed the treatment..

As you mentioned your tooth is having deep caries,but for that one should have to go for a x -ray for investigation for proper diagnosis.and if it is involving pulp than only one can go for RCT. and other factors like, remaining crown structure all are factors to be consider whether tooth needs to be extracted or rct. and as far as pain is concern,if tooth goes for rct than once the BMP (cleaning of pulp canal) done.....your pain will subside,gradullly.

In your case, it maybe acute conditions or hot tooth. So in this conditions first we give  antibiotics and pain  killers atleast for 24 hrs but sometimes for 3days. Then we start rct. Sometimes proper nerve block failed due to anatomical landmark error.

Due to deep caries in the tooth the tooth may develop chronic symptoms of pain even to pressure. If the tooth has good structure and can be saved. Don’t think of extraction as once the tooth is gone its forever. Consult ur dentist again to have a proper anaesthesia and then go for painless rct