What Causes Vomiting And Severe Constipation In A Child?

My daughter who is 4 had type a influenza about 2 months ago. Ever sense then, she seems to contact a bug she will throw up in the middle of the night. It will only be about 1-3 times she will through up. She has been running a fever too. She will then seem to recover but her appetite has changed too, she has been tired as well, and crabby She does suffer from frequent constipation, to the point were at times when she has a bm, it is very hard and she gets fishers from the harden stool.