Hi boots,
Sorry to here you are struggling with CD... It can really be annoying at the time you go through a crisis.
Pretty much, fistula are like "tunnels" that links a source of inflammation/infection, with another cavity (it can be your intestine, the skin, a hollow organ like the bladder, etc. I once posted that to another member to help understand what they are:
... Fistula can be of various "form" more or less intense lets say. Some can be small, some can be big. It may be draining puss, cause well, what happens with a fistula is that the intestine wall get kinda "destroyed" by ulceration through all the layers [there are 3 distinctives layers that constitute your intestin]. It makes a hole and dig a tunnel that reachs through other organs/skin. Therefore its like "infection" (from the crohns ulcers kind of), that the drains Mix of mucus and digestive acid. If the hole is big enough, air/fecal matter can go through. I know it may sound a bit extrem but that is what it is. It sounds bad like that but that is to clarify it.
Fistula can be there without causing pain as long is it does not affect nerves so it can be tricky to consider them a problem at first but they should be taken seriously because of the complication they may cause.
All together, they mean that the crohn treatment needs to be more specific if I may say. Unfortunately, you can't simply rely on melsalamine for your initial treatment (Pentasa/Asacol) as they have no effect on treating fistulae. So the initial approach will generally be the immunosuppressant (ie: Azathioprine (Imuran), Mercaptopurine (Purinethol / 6-MP)) sometimes methotrexate but this is less common for fistula.
Then, the other possibility are the biologic drugs such as Cimzia, Remicade, Humira. These are really good with fistulizing crohn and they can sometime be used in pair with the immunosuppressor.
Antibiotics are often prescribed, as they will control the inflammation/infection and will help allowing the "tunnels" to close.
You will have to keep in mind one thing as well. The most annoying part of fistula is the fact they won't "disappear". They can become inactive, but they can reactivate at any moment if I may say that. That is why you need a specific treatment to keep them in remission. They will be there, but they won't cause issues. I know that at first, when I got mine (they were reaching the skin so I could see them), I took a course of antibiotics and they did close, the skin even grew over them. I though they were gone for good cause well, I had not been told that they actually never leave. And well a few months later, all came back. Point is, they only REAL treatment is surgery. Even if it sounds really scary it can sometime be a really good option as it give actual remission for a while.
I hope this sounds clear, if it does not, just ask, we will gladly try to clarify any interrogations.