ADHD and Vyvanse

My daughter was diagnosed with ADHD on Thursday, and her Doctor put her on the new medication called Vyvanse....she has been on it since Saturday, and it seems like it might be too strong for her....shes on the lowest dose possible, but she just seems like she has no energy. she is having some of the side effects...no appetite, upset stomach, and insomina....she didnt go to bed until after 4 am this morning...Should I keep her on this? or take her off and just deal with her being extremely hyper? anyone else's child taken this? did they have any side effects? did they go away after awhile...if so, about how long did it take...I just dont know what to do...The only reason why my husband and I agreed on treating her with meds, is because of school, shes been having trouble sitting still and concentrating...I guess Im just looking for some advice on what to do...Im so new to this, and this is the first medication that she has been on...anyone have any advice for me??? Thank you.