Can dehydration cause you to go onto convulsions?

A few weeks ago I went to a rock concert with some friends , a couple hours had passed and the last band was setting up their equipment when I started to feel extremely dizzy and mildly nauseous, the next thing I remember was waking up on the ground with everyone staining around me freaking out. My friends told me my eyes rolled back Into my head and I fell to the ground going into convulsions for a few seconds and then i regained consciousness. After I woke up I was still light headed and very disoriented for about 10 mins and then I was fine after that. None of us brought money with us so we were not able to get any water at the show, also we had been drinking a good amount of alcohol before the concert. I'm 21, don't take any medications and have never had this happen before and I'm thinking it was due to dehydration but I wanted to be sure I wasn't something else...