Lower abdominal discomfort, ultra/ct scans, bloodwork, esr, pst, colonoscopy, celiac hla typing, celiac panel all normal. Can it be ativan (lorazepam) withdrawal?

It is nonspecific sy. Your symptoms are not anything serious to justify anymore testing, as you already have done a lot. I would hold off any further interventions and eat and live normally. Begin to exercise daily would help to get your mind of this vague symptom of abdominal discomfort.