I'm sorry you're struggling so much, but I agree, again, with Dayvid.
Anxiety feeds off uncertainty. So it's fitting that you've chosen to fear a disorder (epilepsy) that, as you say, cannot always be properly diagnosed, and can come on at anytime for any reason. That's a perfect HA fear, because you can fear it literally forever.
What you can do (again), is get off the epilepsy boards, and look into anxiety treatment. What have you got to lose? Give it six months, and if you're still feeling the way you feel today, then revisit the problem.