Nanners is correct, I have crohn's colitis which simply means crohn's affecting the colon and for me it has often affected my rectom as well (proctitis), this can be very common for those that have large bowel involvement with their CD (crohn's colitis) or there are many that only have mainly their rectom affected but can also have other areas at the same time affected. When I first became sick it was affecting my anus (which is where my disease actually started) my rectom, colon and TI all at the same time and it remained that way for the first couple of yrs (I was quite a mess), since it cleared up in the TI it has stayed constant in my colon and anus, comes and goes in my rectom and I've had CD for 18 yrs straight now with no full remission.
Do not be fooled, chances are more like you have CD affecting your rectom and not a misDX of it being UC instead...regardless where the inflammation is affecting the pattern will be the same, patchy and usually deeper inflammation with CD, but with UC the entire are will be inflammed but on the surface of the lining only.
Thing is, the treatment is the same for CD affecting the colon/rectom as it is for UC, if you're having rectal inflammation you need to get on rectal meds ASAP to help nip it in the bud, cortifoam is the only rectal med I use, since none of the others ever had any affect on me and I would just get worse and worse making it harder to clear up.
And in the future as soon as you suspect rectal involvement (usually discomfort, incomplete evacuation feeling, excess mucus and/or blood are all good indications of rectal inflammation/disease, then you need to get back on rectal meds right away. Symptoms for UC proctitis and CD proctitis are identical as is the treatment.
My bum is broken....there's a big crack down the middle of it! LOL :)