What Causes Pain In Stomach?

Hi. First off I just want to let you know I am bringing my child to the physician tomorrow but I am just worried. My 11 year old girl had had c/o hurt stomach hurting for the past two weeks. First I thought it was constipation so I have her a laxative. She did have results and has had a regular bowel movement since. The pain went away for a couple days after. She then stayed having c/o pain again and is now vomiting about once a day since last Thursday. She has no appetite. Has been afebrile the whole time.