Hello, About A Week Ago I Was Standing In Line

Hello, about a week ago I was standing in line and felt very hot and dizzy and then got a ringing in my ears and fainted. I used to have seizures when I was little (about 5 years old) and they never found out why I was having them. I am young and healthy and have felt like this before but it never got to a point where I fainted. I am young and healthy. I still feel very weak and dizzy and short of breath and my heart feels weird. All of my blood work came back fine. I just want to feel better.
Thanks