Just a few questions ben11…
What state do you live in?
Why was your son on antibiotics in the first place?
What antibiotic was he was on?
Do you have a family history of UC or Crohn’s?
Does your son have any EIM’s (Extra Intestinal Manifestations)...rashes, sore eyes, joint pains, headaches…over and above his cramping, diarrhoea and fevers?
You have been given loads of great advice so I will just add my views:
Unfortunately no test is fool proof but scoping does remain the gold standard in achieving a diagnosis of IBD simply because the GI can see the bowel for themselves and they can take biopsies of tissue. This is all good and well provided you tick all the diagnostic boxes on pathology and you have disease located in the areas of the bowel that can be reached. For UC scoping is fine as a stop point as it doesn't extend beyond the large bowel, however, as has been said, scoping rules out almost all of the small bowel where Crohn’s disease most frequently lurks. For some the only way to obtain a diagnosis of CD is via imaging. Each has it own advantages and limitations.
Ultrasound - no radiation but not as precise as scanning.
CT/E - Radiation, but allows a for a more complete picture of the abdomen both of the bowel and the structures of the abdomen outside it. It is a much faster test than MRI and radiation exposure can be wound down.
MRI/E - No radation, same advantages as CT in visualising the bowel and abdomen. The trade off for no radiation is a much longer scan time.
Pillcam - The next best thing to a GI actually seeing the bowel. Limitations are it is not suitable for everyone, a patency test (dummy run) should be done first. Pictures are of the surface of the bowel only so is be best done in conjunction with abdominal scanning. This is also the case with scoping, if CD is suspected then abdominal scanning should also be done as a complementary diagnostic tool.
If you have a family history of IBD then perhaps you could pursue an ASCA and pANCA blood test. Again it is not full proof nor diagnostic as such but it may help answer questions.
One thing to bear in mind is it is not uncommon for symptoms to be present before physical changes take place within the bowel. With that on board and should answers remain elusive, symptoms persist and a diagnosis of IBS is it then I would keep a diary. These are suggestions as to what to include and the information is in the forum wiki, click on the link:
Diary Inclusions
Dusty. xxx