Have your son write kites/requests about this. Keep trying to work with the prison doctor. Contact Michigan Corrections office for Prisoner Health Care at (517) 373-3629
Clark County, NV practitioner.
Your son is a ward of the Department of Corrections. I would suggest hiring a lawyer who works with the MDOC and can assist you in pursuing an administrative action to see he gets proper medical attention. It is critical to document the medical concerns and history to the MDOC.
The answer to this question does not constitute legal advice nor does create a client relationship with the attorney answering this question. For more specific advice regarding your situation, please consult your lawyer.