Potentially a fistula?

Okay, so I have been having a chronic what seems to be at least a fissure for a while now. I was also recently diagnosed with Crohn's disease. I have rectal bleeding and the area is very tender and there is anal tissue protruding. It's always really itchy, and sometimes the itchy-ness will keep going and make my vulva very itchy. I tell my doctor this and he says it's unrelated, but after having this happen for so long now it's hard to believe it's not related. I have been tested and do not have any STD's that could cause the itchiness either. I'm on Flagyl right now, but it doesn't seem to be working. Actually the anal fissure seems even worse, even more itchy and painful. If anyone can give me any ideas to what's going on it would be appreciated. At least then i might have a direction of what to ask and where to go. Thanks!