How long does it take for the fistula to go away?

[Mamba]

I’ve just had a root canal done on my front upper tooth as an infection was discovered on the apex of the root of this tooth.
The only reason I went initially was because there was a persistent small pimple on the gum above this tooth, I had no other symptoms whatsoever.
The root canal was done two days ago, but I still have this pimple on the gum, does that mean the infection is still there and would need another RCT done to get rid of the infection, or do they take a while to heal and go away?

 

[MattKW]

The pimple should stop oozing pus within a few days. If the draining sinus (not actually a fistula) was there for a long time, you may be left with a small, hard scar about the size of a pinhead - nothing to worry about.