Hi Sailorluna...
It's usually either one of two culprits, of which both have been mentioned:
a) Your seton-knot could be caught inside the fistula, and the fistula might be becoming inflamed because of the general foreign-object like-quality of butt-piercings. The body doesn't like those. So sometimes, when the knot gets into the fistula, or sometimes even when it's not, the skin will enflame and go a little nuts. I'd call your doctor.
b) Your fistula could be closing around the seton. They don't always work as intended, and different surgeons use different types. My colorec prefers long, plasticy, flat ones, because the fistula has a harder time closing around a flat seton than a circular one. Otherwise, you could have an alternative pocket in there which the seton will not help. When I had mine placed, the surgeon actually carved a second fistula out, because there was a pocket of stuff that the seton wouldn't drain. When she carved it out, she made a path from the skin, to the seton'd fistula. Hurt for a while, but it kept me from having an abscess AND seton at once.
As for the epsom salts: How is your post-op healing going? Is there a lot of granulation tissue? Do you have a sitz bath? Initially, I was told to only use a little less than a table spoon, because the granulation tissue is really sensitive. However, now, when I'm in pain, I use probably two tablespoons, mixed in good with the hot water. If I'm getting a bath, I usually pour in a cup or two, depending on how much water is in it.
As for the yanking that was mentioned: excellent idea. But you don't have to yank hard. I just slowly pull on it, until it's uncomfortable. Then, I slide it in and out (pull out of the fistula, by gliding your finger along the seton and making friction) for a few minutes, and I'm good. Of course, do this in a hot, salty bath. Keeps the pain low, and the holes dilated.
Good luck.
