My understanding is that Crohn’s-related fistulas cannot fully heal until the inflammation in the area goes away, which can take a long time even when you’re on the right medication. I have a fistula that periodically heals over, then becomes an abscess and eventually ruptures (or gets so painful that it needs to be surgically drained), and the cycle continues. It sucks. It would be a good idea to talk to your gastroenterologist or anorectal surgeon about this, especially if you’re experiencing a lot of discharge from it on the regular.