My six year old daughter had been throwing up for three hours. she also had some bm when she vomits. when should i go to the er?

Confusing question: If you mean she is throwing up stool, an er visit is indicated.If she has pooped during a vomiting episode is is less worrisome. Try to get her to suck on some ice chips or popsicles to calm the stomach. A little cola in a shot glass full if ice chips can occasionally settle them. One ounce at a time of 1/2 strength gateraid or similar product can help.Seek help is no urine output in >8hr.