I researched and I cannot find any English speaking doctors that can perform written assessments beyond a regular doctor's note. Perhaps there are specialized services out there.
I am not referring to general health assessment like the type employers give out, nor 人間ドック that focuses on preventative diagnostics. The questionnaire and assessment are already determined, meaning the doctor have to read and answer the exact questions in English on that form.
An example would be National Medical Clinic but that's still not quite it.
https://www.nmclinic.net/index1jp.html#our_servicese_jp
A medical specialty is not needed (eg. say dermatology or ENT or gyno) – a general practitioner is fine.
by deltawavesleeper