My 16 year old daughter has been complaining of upper stomach pain, she has had nausea and vomitting and not ate much... this is going on the fourth day...
Pain is below breastbone and central and severe.

What does the pain feel like? Is is sharp, dull, aching, burning? A common cause of epigastric pain is an ulcer or gastroenteritis. However if the pain is not getting better with time then she needs to seek medical attention. Abdominal pain is not something to play around with. With abdominal pain, only labs and CT's and actually find the cause and the reason for the pain.

First of all I need to know how she feels like, I mean sharp or aching etc. because I personally feel its due to ulcers or gastroenteritis for sure. Tell her to drink more water and fruit juices. I hope she feels better with it, but if her Upper Abdominal Pain gets severe then you have consult an doctor.