@caringwife, I believe you may have a couple of options.
1. If Ken's doctor is willing to pursue Mayo Clinic in Rochester, I would accept his offer for a physician referral to another relevant department. Immunology or rheumatology may be an option if the GI department cannot see him. At this point in time, several departments receive more requests than they have capacity. But it doesn't hurt to try.

2. You may also consider the Mayo Clinic Care Network https://www.mayoclinic.org/about-mayo-clinic/care-network/about
The Mayo Clinic Care Network is a select group of independent health systems that are granted special access to Mayo Clinic's extensive knowledge and world-leading medical expertise. In South Dakota, Monument Health https://monument.health/ is a Mayo Clinic Care Network partner.