The symptoms are serious and you have rightly been sent to the stroke clinic for a CT/MRI to exclude a brain event.
If you suffer from rhinosinusitis you must let your doctor know so that a sinus CT is done at the same time and obviously to see the position of the plates.
If you are on steroids
or any immunosuppressant drug, they should be reviewed urgently as the symptom can mean a temporary loss of blood supply to the brain that is often caused by medications. As i said 'temporary' the recovery is usually 100% but all tests must be done especially if you have risk factors of heart disease
to metal plates is a hypothetical possibility, but never actually proven in real life in most patients who have 'allergic' reactions after metal prosthesis