I feel physically exhausted

I feel weak all the time and confused. I get headaches, fainting episodes, seizures and mood swings. I have been experiencing these problems since I was a teenager and I am now a young adult. I feel like I am just fading away and I can't carry out normal activities. It has robbed me off my life and I feel like I'm not really there 24/7. I had these problems throughout school without knowing it. Sometimes I wonder how my life would be if I didn't experience this. I would be a completely different person and would not have to worry about how I come across or present myself to the world. I just feel tired and exhausted by life.