Sunny seems like you can pretty much pinpoint the circumstances that lead to your DH having a seizure, pity the Dr's can't work it out.

I would still ask your Dr about any side effects, while I don't know of any males who take medication for epilepsy a GF of mine has it & the medication she was on caused her heaps of trouble when pg ~ she had two miscarriages & her little boy has got a few troubles that they reckon are caused by the medication she was on whilst pg. But hers was too bad for her to come off the meds for the duration of her pg ~ they tried a couple of times over her various pg's & all with terrible results. So yeah certainly look into it just to be on the safe side.