Well, hopefully the fistula has healed and won't bother you again.
My son had a few fistulas, one stopped draining about 6 months ago and according to his Dr (whom we just saw last Tuesday) it has healed over with nice new pink skin and should not bother him again.
His other fistula keeps draining slightly- and sometimes nothing - but it is right where the abscess was, apparently there is quite the crater there (again, according to his Dr.) that has new skin on about half of it, but until it stops draining it should not heal over.
If your fistula stopped draining before it healed over I THINK you should be okay, are you on any meds?
Also, I had my sons GI take a look to see if there was anything else forming, or if the other fistula was closing over too fast to make sure that he doesn't get pus trapped. Thankfully there was nothing and he is SLOWLY healing.
Might be an idea to get your Dr. to take a look just to make sure.