Appendix inflammation (appendicitis) is usually much more painful than simple abdominal discomfort. Unfortunately, all the diagnostic procedures you’ve done (an ultrasound, colonoscopy) can neither prove nor deny appendicitis. Diagnosis of acute appendicitis is clinical in nature and is made according to the symptoms and signs shown by the person experiencing the pain. Therefore, diagnosis of appendicitis remains very uncertain because many other abdominal disorders manifest the same symptoms (abdominal pain, temperature, vomiting, nausea etc.). Sometimes even healthy appendices are surgically removed or something else is found during the operation because of an incorrect diagnosis of acute appendicitis.
IBS can manifest with many symptoms including abdominal pain or discomfort.
You can wait until all medical reports are completed before thinking about diagnosis and treatment of the condition.