I'm not sure I understand why the JME diagnosis was thrown out--I have JME, having my first seizure at age 19 over 15 years ago. I can go for well over a year (when unmedicated, although I am on lamotrigine now which controls them) without having a big (tonic-clonic) seizure, and my EEG's are normal between episodes (I have myoclonic and absence seizures a bit more often, but they aren't so noticeable and I still have normal EEGs between them). Many people with normal EEG's are still diagnosed with epilepsy.
Further, regarding your concerns over your daughters drug use: lack of sleep, for most of us (with JME and other seizure disorder conditions) is a pretty big trigger, and in adolescence and young adulthood, it's common to stay up late studying or out with friends, whether alcohol or drugs are involved or not. Note though that this is just that: a trigger, not a guarantee it will result in a seizure, eg, likely during her 7day EEG there was some sleep deprivation asked of your daughter (to provoke an abnormal EEG) but just because she didn't experience an episode with the provocation doesn't mean her brain waves are behaving normally at the time of a seizure.
Of course, it may very well not be epilepsy, as you didn't describe her seizures (tonic-clonic, drop attack, etc--did anyone witness these events?) and could be isolated syncope events which are also not uncommon in adolescence, I passed out at 18 when I got a my ear pierced... So, who knows. Just wanted to give my experience with JME and EEG's. I've had good neurologists and bad, informative and uninformative and its worth going to a couple-few to help put your mind to rest. Be sure she mentions anything that may be neurological even if it seems unrelated.
Best of luck to both of you
My son has seizures that are not being treated by ,medicine know matter what medicine we have tried.This June he has the VNS put in and it has to be turned up every time we go to the doctors. And still on medicine .
The other thing I did was to give him Omega 3-6-9 Vitamins and B6. He is also on medicine for high blood pressure medicine to see if that helps him. Because as we know stress and anxiety along with lack of sleep causes Seizures.
I have a friend of mine who son was on medicine for seizures and then taken off because he was not having any more Seizures.Then I day his mom said he was fine ,until about 5 minutes later she went to where he was and he was on the floor and she had to call 911. Her woke up and wanted to know why he was at the hospital she said. The Doctors told her that it could be because her son was trying to do to many things,like finish high ,work part time, and pick a collage to go to.And that he should slow down some. Last time I talk to her she said her son was doing good and taken a new medicine and always making sure he was around people in case something where to happen.
There are so many different kind of seizures,with my son you can't see them all.The only way you would know is if he was on a video eeg and others you can see.
god bless. The thing that has helped me is to pray and talk to others.