In the morning I ate my breakfast and moved to my office there I fainted and my friends took me to the hospital they injected and gave some tablets for dizziness, I was very much worried that what makes me to faint even after having my breakfast, today morning I am having high fever please tell me what it could be.

It is probably a virus or infection of some kind. Perhaps you have the flu. You should follow up with your doctor. Depending on where you are, there are many things you could have been exposed to so it's hard for us to know online.