I had root canal in 2015, still painful – how can I trust doctors after that?

I have root canal treated on 2015 but the pain never stopped
Now it become even more painful that I can’t handle it any more my face is swilling and the X-ray show there is over filling into my maxillo sinus cavity which infected
What is the best thing I can do
Becouse the doctor talked me that it is complicated because of my face anatomy
And he told me that I am the worst case scenario
Iam young and that herts me more because I stay away from society because of my face swilling
The pain rate is 8 of 10
We’re can I go
And how I can trust doctors after that?