Hi there. This is most likely bell’s palsy from the description. If someone has Bell’s palsy, the muscles in their face become temporarily paralyzed. It usually affects just one side of the face. Symptoms appear suddenly one cannot shut eyes and their mouth droops. These are worst about 48 hours after starting. Scientists postulate this as a viral infection, which is making the facial nerve swell, or inflamed. it is more common in diabetics, people sick with cold or flu and pregnant ladies. Most of the people improve without treatment. Most of the sufferers begin to improve in 2 weeks and completely by 3 to 6 months. So do not worry and take care.
Hi,Please check your father in law for the presence of airborne fungus called cryptococcus gatti in his system.
It sounds like you need a new doctor.
The person who said "it sounded like an airborne virus" needs a psychiatric examination.
It is possible it was a manifestation of Bell's palsy. But an MRI is still indicated.
If your father-in-law did not have both an MRI and an MRA he needs one as of yesterday. Preferably at a stroke center.
And in addition to a new physician a good tort attorney specializing in malpractice.