I can certainly understand your feelings of fear and anxiety about this. I know I went through that for some time re a fistula as well. I don't pretend to know but it does seem like getting a new fistula might point to Crohn's? However, there are a number of things that can be tried. When they thought it might be Crohn's I was told a biologic might be a good option. Also, there is research being done (American trial) on stem cell fistula closure by a doctor at the Cleveland Clinic. Other alternatives I was presented with was a procedure done by Dr. Shen (now in New York apparently) as well as advancement flaps and a surgery involving the gracilis muscle.
I mention these just to let you know that there may be solutions. However, having said all that, I have opted to just live with mine (pouch/vagina fistula). It really helps to keep the stool on the thicker side (I use psyllium) and also to make sure I don't let the pouch get too full.
I really do feel for you as you go through this...