My 16 year old daughter is vomiting diareah 101 fever stomach pains and back pains....what could b the problem?

V/D, fever: The most likely explanation is an intestinal viral illness, people commonly refer to as a "stomach flu". Usually lasts 2-5 days and no treatment other than keeping hydrated. Also possible are urinary tract infection/kidney infection, appendicitis, pelvic infections if she is sexually active. More rare things would be stuff like gall bladder or pancreas infection, hepatitis. Call doc if pain severe.