I'm sorry you and your fiance are going through this. But what he really needs is to see a neurologist. Just getting a few tests done in the hospital and being given meds is not enough when someone is having multiple seizures. He needs to see a neurologist or and epileptologist so that his condition can be monitored, medications can be adjusted, and he can have more tests done. Did they say what they found on the EEG? Sometimes EEG's come out negative, but that doesn't mean there is no seizure activity- it might be too deep within the brain for it to register. If he has a doctor he is seeing regularly, the doctor can order more than one EEG if nothing was found, or they can even send him for a video EEG (they'll hook him up to an EEG machine and also will video monitor him in the hospital for 72 hours or more). The doctor will also want to see the MRI he had done and any blood tests. I guess what I'm trying to say is that your fiance needs continual care, not just once from doctors in an ER who are not specialists and who are usually kind of rushed to get through so many people.
Keep us updated on how he is doing.