Is my dad having a stoke ?

one of his eyes (my left, his right) is INCREDIBLY droopy, and he says that he'll go through periods (usually after he has woken up) where he can see, and then randomly its like someone pulls a curtain and he goes partially blind again. it is really cause for concern, because he is already blind in one eye from a freak childhood accident, and now he can't see out of his good eye. he says there is dizziness ociated with this phenomenon. please help! aaahhh!!