So a CT scan and/or MRI isn't going to show anything after the fact. Your daughter needs to get in to see a neurologist, and have what is called an EEG. The nurse hooks all these wires up to your head, and then runs a scan, to look for seizure activity.
When I was 23, I was woken by my GF at the time, who found me passed out on the floor. Went to the hospital, no issues were found so they sent me home. Two weeks later she sees me having convulsions in our bed, and I've been on Dilantin ever since.
Word of advice: If and when you are able to get in with the doctor, if they just blindly throw dilantin as the only solution, look into other prescription medications first. Dilantin destroys teeth from the inside. But, it's worked for me for 22 years now.