Sad to read that getting proper medical care is so hard for your FIL.

Some clinics/hospitals offer for far away patients a one stop shop service.
I.e. patient can be admitted for one or 2 days to have all examinations and tests done. Upon diagnosis a treatment or management plan can be made up which the primary care physician should be able to execute and follow up provided no in-hospital procedures are required.

Hope this helps.

Kees