OK, we're patients here, not doctors. But it seems even your specialist isn't yet in a position to make a diagnosis, other than "not bowel cancer". "IBS" isn't a diagnosis, it's an etiology, i.e., a set of persistent, collective symptoms that is described under the title "Irritable Bowel Syndrome".
The terminal ileum is the place where the small bowel widens and becomes the ascending colon, on the right side of your abdomen. The colonscope goes in at the anus and can go right around (from left to right) until it reaches the caecum, which is a pouch that collects the stuff from your small bowel, on its way to the colon. The stuff (called chyme) is squirted into the colon by means of the ileocaecal valve at the top of the caecum.
So it seems that's the area where the scope saw your ulceration. If that hasn't cleared up, you'll keep getting the symptoms in that place. That "dull ache" could be a partial blockage caused by those ulcers.
There's a lot more testing to go through before you get a conclusive diagnosis of something. The likely contenders will be ulcerative colitis (UC) or Crohn's disease. A Crohns diagnosis comes if you have chronic inflammation sites in the small bowel alone or both small bowel and colon, and/or in the mouth, oesophagus, or even other parts outside the digestive system. If you have persistent ulceration only in the colon and rectum, the diagnosis could be either UC or another variant known as "Crohn's colitis". Both conditions, along with diverticulitis, come under the umbrella of "Inflammatory Bowel Disease" (IBD). Note, IBS does not mean IBD.
To look at what's happening in your small bowel, you could be sent to a radiologist for a CT scan, an MRI scan or an enterography. During a diagnostic workup you would have repeated blood tests to look for (and monitor) markers for IBD. The two most interesting markers are CRP and ESA but white cell and red cell counts and creatine level are usually included, as they can be interesting, in combination with high levels of CRP and ESA.
So -- when the specialist decides to get going on a diagnostic workup, there's a lot of procedures to go through. How long before you can make that follow-up appointment? From the information you have given, it seems you need to be seen sooner rather than later. Were you given any medication to try to reduce/forestall inflammation? Any directions as to what to eat/avoid?
