Dear sir, This condition maybe or may not be related to the treatment done earlier. Sometimes it is just pure coincidence that the area which received dental treatment gets affected with some other infection which is in no way connected to the tooth which was treated. And since you have already told that your dentist has checked for the problem and initiated a treatment I don't think you should worry about that anymore. In case your problem still persists, please consult on this platform and I will be glad to help you again

Dentist should remove all the guts percha cones nd put you on antibiotics till the infection subsides nd the nasal discharge has completely stopped ... After that he should check is there any direct communication between sinus nd nasal floor ... Nd then should go for obturation again ...