Mentally sound, physically weak from falls and poor diet. A couple of weeks getting nursed back to health with therapy and a healthy diet would do wonders. His doctor is not proactive or helpful. My brother lives by himself, is on social security and does not have a social worker. How can I get a social worker? My brother is 59.
Is your brother weak because of specific medical conditions or because he's not able to prepare healthy meals? Or is he diabetic? Either way, Meals on Wheels would help if he qualifies. You could also get him some Boost or Ensure to drink. Opening a can is easier than preparing a meal.
I'm not sure a social worker could prescribe PT, but one might be helpful for his general overall wellbeing. Ask his PC doctor if he has one.
Usually a doctors office (geriatric care, internist, etc) sometimes has a social worker on staff.
Otherwise, visit your local senior center, etc and see if they can recommend someone to evaluate brothers home and living arrangement.