Well, despite what your surgeon may have done, you can still have a lot of bile sneaking into the region where your resection was and it could be irritating it. there is a powder they prescribe for this, you just mix it in some juice and you can take it 2-3 times a day depending on how bad it is.
Otherwise, your disease still might be active. we have similar stories, and mine grew back so quickly even while i was taking imuran. you're probably going to need a colonoscopy if you have not had one already or a small bowel series. CT scans are useless sometimes. My feeling is that you are having flares in an area that has been repeatedly operated on (which means its actually quite narrow b/c you dont have a cecum) and it could feel different from ones you have had in the past because its now developing in areas where it was once not diseased.
Another thing...are they absolutely sure this was an infection and not inflammation?
Other thing to think about...
ovarian cysts...which can cause women a ton of pain and mimic infection symptoms. it's in the same area. they probably would have seen those on the ct scan, but like i said those tests can miss alot. perhaps see a gyno??