If you haven't found any answers yet, I would research any medications you are taking, especially those for your seizures. I have never in my life had any sort of sleep apnea until my doctor put me on the nerve medication gabapentin. the same sympoms you are describing happened to me, and I would come flying out of bed gasping for breath just after falling asleep, sometimes I would just have to stay up all night long because the minute I fell back asleep it would happen all over again.