Casey was foaming at the mouth and catatonic. Crystal's seizures have not been diagnosed (as far as we've been told, that is) and if they are drug-related like so many allege, that will certainly come out in the wash.
Since there are so many reasons why an otherwise healthy and vibrant young woman could have a seizure, we have to wait for someone to give us information. I'm sure there will be plenty of people who will say that the information is false (depending on who delivered it) or it satisfies their need to know. Whatever else, that she had one 6 weeks before she had the next one, which was followed in close proximity by another one, is cause for alarm. One can be dismissed as an anomaly caused by any number of factors. Two in succession like these this week are reason to assume a more serious situation might be in play.
It could be as simple as too much caffeine intake. Could be stress. Could be hormonal. Could be metabolic. Could be neuro-electric. Could be a lack of sleep or bad sleeping patterns. Could be a bad diet. Could be any thousands of reasons, and I'm more willing to allow for those factors before sliding down the slope of drugs.
I had two seizures a long time ago because I was dehydrated.... yeah - not very glamorous, but they can happen from the simplest of things.