I am not sure. My guess is that it could be the medicine just as easily as the disease. I have found that the side effects of most of the medications are nearly as bad as the seizures themselves sometimes.

Dilantin (another name for what you are on) can cause this:

Ataxia: Wobbliness. Incoordination and unsteadiness due to the brain's failure to regulate the body's posture and regulate the strength and direction of limb movements. Ataxia is usually a consequence of disease in the brain, specifically in the cerebellum which lies beneath the back part of the cerebrum.

Does that describe what is happening to you?