have you looked into and medications he's taking? a lot of meds have those side effects and many taking together can cause those symptoms. just a thought cause we've been through this with my dad and his depression meds and heart pills ;)
The symptoms you mention could be signs for vertigo. However, often times vertigo is also just a symptom of something else. If the meds.does not help, perhaps it is time that you seek a second opinion.
He doesn't take any other medications, this last time he took a pill was probably 10 years ago.