I am really scared. i have symptoms of acute brain swelling. how long does it take to lose consciousness from that?

Get seen now: Brains don't "just swell" unless it's the result of a blow, especially a second blow. I would not be surprised if you are siimply hyperventilating. If you still believe you are seriously ill, phone your physician's office or otherwise get seen. Acute cerebral edema announces itself as headache, impairment of consciousness, and nausea / vomiting.