I AM very sick and i dont know whats wrong

i have not been feeling well for the past week. my legs have been really weak, i get really dizzy, i feel like im going to pueak some times, i have vomited, i have fainted about 4 times, i have been really out of it meaning at school just really down/tired/lazy upset, i havent been getting much sleep, i fall a lot, i cant seem to get work done. I dont know whats wrong i feel like i can barely walk and i need answers fast. i have not been feverish but i have had extreme stomach aches. PLEASE HELP ME!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!