My 5 year old is throwing up blood?

I took my 5 year old daughter to the doctor on 12/29/08 for her not feeling well. Found out she had strip throat, bronchitis. We then had to take her to the ER because she started throwing up blood. They found blood in her stool and did some test, they said nothing was abnormal with the test just a couple of the test were above and below normal. At the moment I can't remember what the test were because we literally rang in the New Year at the hospital. They also took x-rays and found nothing wrong. They sent her home because they didn't know what was going on and said that the GI doctor would call to make an appointment sometime later to check. Well the next day she threw up blood again. Again we went to the ER, they sent her home again because they didn't know what was going on and said that it sounded like the lining of her stomach was upset. She also has severe stomach pains and has not eaten much since then. Am I over reacting?