Hi.
Thanks for your query.
Noted the history about your 13 years old daughter and understood your concerns.
Vomiting, dry heaves the next day followed by diarrhea and
severe pain and tenderness in abdomen in an young girls can most probably be due to the following reasons:
Gastroenteritis as this started with vomiting and progressed as you have mentioned.
The pain and tenderness in the abdomen could be due to severe enteritis but few other things should be ruled out by the following way.
Get an
ultrasound of the abdomen done as soon as possible and this may need a visit to the ER.
Clinical evaluation and examination by the DOctor, preferably a
General Surgeon can help the most.
Other tests of stool, urine and blood will help to get a proper diagnosis and a course of a PPI like
Omeprazole, antibiotic active against intestinal infection can help to alleviate the problems if it is due to intestinal infection.
But if there is anything that is surgical, may need a surgery.