@elynnbish this must be so difficult for your son and you. And he’s been suffering with this for 2 years with no answers? And such a difficult age! Have you been to Children’s Hospital of CO before? I know it’s a 4 hour drive but hopefully, you’ll get some answers. And directly across the street is University of Colorado medical center.
https://health.usnews.com/best-hospitals/area/co/university-of-colorado-hospital-6840430. This report shows that UCH rates high in immunology.
Ask your doctor (the gastroenterologist, since he’s been helpful) for a referral to both hospitals.
I really hope you find some answers, soon
Is this something you could try?