UDN is a good thought, and I think worth looking into. I hope this suggestion gets upvoted more. They have great success stories and are run by great people. It also illustrates that "I am at Harvard for medical care" can mean a bunch of different hospitals, clinics, and doctors, who all have varying expertise and areas of focus.However, a couple things to point out:It's a research study, so not the same as "having a doctor." You also need a study recommendation letter from a health care provider."We cannot accept all applicants." Eligible participants "have at least one objective finding." I honestly don't know how they define that, e.g. is weight loss objective enough?"After all of the necessary information is received... it typically takes 6-8 weeks... to decide whether to accept...."They have about 12 clinical sites across the US, not just Boston.Not trying to dissuade OP. If it were me, I would absolutely be looking at UDN. Let them decide whether you're eligible or not. I'm just trying to provide perspective about what to expect.
Since you're already in the neighborhood, have you tried this group? https://undiagnosed.hms.harvard.edu/