Mer, it's good to see you here again!
My mind immediately went to side effects of the Topamax. When I consulted my Mosby's Medical Drug Reference, it states in side effects: cognitive dysfunction and defective coordination (81% in one study!) Sometimes meds produce worse problems than the one they're meant to treat. They also mention drinking plenty of water to prevent kidney stones.
However, with what the others have said, it could well be an infection or stroke. Keep pushing the doctors to find out what is going on!
Mer, that does sound very suspicious for the Topamax. I think they should back it down again and see what happens.