Hi Paiges,
I have crohn's colitis, and yes, it's crohn's disease affecting the colon which is why they term it as crohn's colitis, yes you now have an increased risk of CD affecting any part of your GI tract and it can even affect more than one area at a time, it's not super common but it can and does happen to many of us...when I first got sick it was affecting my anus (perianal crohn's skin tags), rectom, colon and terminal ileum (lower part of the small intestine,where it closely connects to the large)...it did heal in my TI, comes and goes in my rectom (proctitis) but has stayed constant for me in my colon and anus (don't let that freak you out too much though, I'm an oddball, allergic or non-responsive to tradtional oral RX and had some issues with my anal tags that long story short, have made it even more difficult for my colon).
Many crohn's colitis patients go into full and long remissions so rest assured that it's not completely the end of the world...the same meds used to treat crohn's colitis are used to treat UC, so nothing new there for ya.
You can certainly share at the crohns forum (I do at both because my CD is located in my colon so there are some similarities there)...the majority of CDers have CD affecting their small intestines over any other part of their digestive tract, so it's a little more rare to have crohn's colitis but there are plenty of us around, infact, many people get mis-DX with having UC when they infact have crohn's colitis (just as in your case, so you're not alone there either).
Remicade is suppose to be very helpful with your type of anal issues (abcesses, fistulas) so it's good that you're on it.
Biggest differences between UC and CD are, the pattern of inflammation with CD has patches (or skipped patterns of inflammation that have healthy tissue in between) with UC the entire are will be inflamed, UC is limited to the colon/rectom and often starts in the rectom and moves up...CD often starts in the small intestines and usually stays there but can certainly appear in any other part of the GI tract from mouth to anus (BTW, my CD started on the anus with my perianal crohn's skin tags, so it goes to show just about
nothing is written in stone when it comes to IBD, except the pattern of inflammation and the fact the UC is still limited to the colon and rectom).
It's a bit of a change for you, just stay as calm as possible about
it though, try not to stress out over the change of DX, you still can go into remission, and all that.
Here is an excellent link that describes the 5 subtypes of crohn's disease....
http://www.ehealthmd.com/library/crohnsdisease/CD_types.html
Copy and paste if link doesn't work, well worth the read.
:)