Hey Summergal! There are many reasons for fistulas. Mine was caused by the incision from my LIS healing the wrong way and forming an abscess. They can also form from a wrongly healed fissure. In both of these cases, the healing forms a 'roof' over the original wound. Fistulas are very commonly caused by abscesses (I read 30-50% of abscesses will develop into fistulas, but don't quote me on that!). Abscesses can form for no serious reason. I don't know if UC is a major cause of fistulas. From what I've read, where IBD is associated with a fistula, it's usually Crohns more than UC. Basically, I don't think you should worry about anything sinister just yet. Of course, I'm not a doctor, so it is a good thing that your new GI is being thorough. I think that her being concerned is much better than her being indifferent and negligent. :D
I'm also still producing some milky white exudate, sometimes it's a bit tacky. There's not a lot, and it is diminishing, but I'm not sure what to make of it.
I've also been bleeding, pretty much for three months now. It's not a lot of blood - just a wee bit on the TP after a BM, and it also seems to be diminishing. But yesterday I had to strain a bit and boy, I bled more than I have in two months! It was like a nosebleed!
I called my surgeon, but I won't hear from him until Tuesday at the earliest because it's a holiday weekend up here in Canada right now. I'd be very interested to know what your docs say is going on in your case because it sounds like we're having similar experiences, but I don't have UC or Crohns or anything like that (so my CRS said!).
I'm not sure what explains our exudate and bleeding, but let's compare notes when we can. You're not alone! I'm SO tired of worrying about my butt too. Soon we will have figured out what's going on and we will be back on track with the healing. Try not to worry too much. Everything going on with us may very well be normal, if a bit slow, as far as healing goes. :D