What Is The Treatment For Stomach Pain And Vomiting?

My 5 year old daughter has had abdominal pain for 2 weeks, no other symptoms, no diarrhea, constipation, vomiting, fever, upper respiratory symptoms, nothing. No uti, had urine culture last week. Has had occasional blisters in mouth off and on for about 2 months. Also had sore throat 2 months ago, checked for strep, had swollen, painful glands in neck. Not sure if all these symptoms are related? Concerned about the abdominal pain, stops her from usual activities such as playing. Describes it as stomach hurting and when asked what it feels like, says she feels like she is going to throw up. Sometimes worse after physical activity.