My 19 year old daugter has an upset stomach and she vomits once in a while she is 120lbs. 5'8'' she eats fairly healthy. She is a college student, and does not drink, she smokes pot. Other than upset stomach she is very healthy.

Stomach pain. The symptom could be from many things . She may not be telling you something. Of course in young women pregnancy always has to be thought of. Other than that it could be anything from emotional distress to an ulcer. For sure periodic vomiting is not a normal thing . People tend to ignore a lot of problems thinking that they will go away. Good that you're asking about it.
There . There are many illnesses - some rare, some common - that can cause pain in this area for a child/ young adult such as: - gastresophageal reflux disease (most likely) - gastroenteritis (stomach flu) - gastritis - peptic ulcer disease - pancreatitis - gallbladder disease - constipation - appendicitis - functional abdominal pain and those are just a few of the things that could be causing it! without knowing more information and being able to examine your child, it's hard for me to be able to tell what's going on and how to direct you to treat her. The safest thing to do is to call her doctor. They may want to examine her or ask you a series of questions in order to figure out how serious her stomach pain is and what to do next.