Can an employer question the nature of a medical bill or your medical background based on a past due medical bill on your credit report?

They may ask if you can do the duties of a job or if you have any limitations.

There are some jobs because of their nature, that require a complete physcial for employment, often truck drivers, pilots, truck drivers police officers.

Also they can ask about your credit and why this bill has not been paid or what payment arrangements you have made.