I wouldn't worry so much about it becoming a fistula. those usually occur when the infection tunnels. If the infection is gone, then you should be fine.
The surgery site is all healed, but my rear is still sore. I have an external hemmie left over from the swelling. It usually behaves itself. any I have the hemmie turned fissure, which is being stubborn and not healing---ARGH! but at least it doesn't hurt too bad. It kinda feels like a paper cut--I just wish it would heal as fast as one!