There are many factors that can cause the upside down vision. In details, if you got a accident that cause braindamage, you may suffered from upside down vision. Besides, brain tumor, infarct or vertical diplopia can also be the factors of upside vision. Still some people who suffered from dimentia may also cause upside down vision. Anyway, if you really suffered from it, you shall consult a opthalmologist or a neurologist ASAP.
I haven't had the upside down vision myself. But I know that upside down vision can be caused by many reasons. Some kind of eye diseases will lead to upside down visions. If you have vertical diplopia, you may suffer from upside down vision too. So when you have this kind of problems, you may need to have your eyes checked by an eye doctor. Besides these reasons, upside down vision can be caused by brain damages or brain tumor. And some kind of viral infection on the brain may lead to upside down vision too.