I don't bother explaining to doctors why I switched. Every time I did in the past they got personally offended and refused to address their flaws, so why bother? Also I am almost convinced good medics in certain fields (endocrinology for example) are almost nonexistent.
Most endocrinologist only ever see diabetics and people with thyroid disorder. They are often quite lost when they get to see something else.
I found only one willing to help, and only in an half-assed manner. I still go most for formality and legality reasons, but I am mostly treating myself as I want now.