Does your child protest going to bed usually and how do you respond when she does throws up? Does she get to stay up later? I work with developmentally disabled adults, who at times, can be much like children and they develop some strange behaviors when they discover that it works to get them attention or escape from an unwanted situation. If you have your child checked by a doctor and they cannot find anything physically wrong with her then it could be behavioral, in which case you would want to give it as little attention as possible and continue letting the child know it's bed time and placing her back in bed after every time. Eventually she will learn that this behavior does not get her the desired outcome and therefore will change the behavior to something more appropriate. Also it could just be that the child is really stressed out about something. My brother used to vomit every morning when he woke up because he was so stressed out about his teenage situation. Good luck with everything!
It could be allergies or it could be reflux. I would take her to her Ped. to let him check her out. Vomiting every not is definitely not normal.
May I ask what she drinks and eats in the hours before bed as it possibly is food related , does she drink Milk as very often that can be the cause and children become intolerant to it.Try giving her nothing but water after she has eaten her dinner and see if she still throws up.may also be some reflux, I would ask your doctor his opinion ..good luck