You said that you had seizures while you were sleeping. I wonder if you are having Nocturnal seizures due to all of the late hrs that you have to drive. You really need to see a neurologist who specializes in epilepsy on an epileptologist. Nocturnal seizures are seizures that happen in your sleep. Since I don't know much about you, I can't help more than that.
Epilepsy is caused by an interuption/injury to the brain. Mine was due to an illness. It could also be due to an automobile accident. You really need to have testing done like an EEG, MRI, PET scan, to really be able to see what is causing your seizures. One seizure doesn't mean that you have epilepsy. If this is an ongoing thing, you may have epilepsy.
Did the ER tell you what happened during the time that you were found in the semi? Were you accually convulsing? Some people have Narcolepsy where they fall asleep in the middle of the day with no reason. You may want to rule things like that out too.