Hello
I understand your concern.
Sudden onset of droopiness of left side of face indicates bell's palsy or stroke.It may have arised as complication of
acute sinusitis causing
brain swelling or thrombosis in blood vessels of brain
I recommend you to immediately have visit with
neurologist.Proper neurological examination with CT scan head will be needed to confirm the diagnosis.
Also his other investigations like fasting blood glucose,blood pressure,blood lipids,ECG will have to be done to rule out risk factors like hypertension,
diabetes mellitus,
atherosclerosis,heart disease.
A simple bell's palsy may resolve by itself in 2-3 weeks.
However,if there is evidence of any stroke,low dose aspirin as maientanace dose has to be started for future prevention of stroke.
Other medical conditions if any have to be brought under control.
Avoid smoking and alcohol.
Avoid sedentary lifestyle,do brisk walking for minimum 30 minutes everyday after ruling out heart problems.
Hope this information helps.
Wish him good health.