Wow, we really don't deal with muscular dystrophy here - but this part of medhelp does. - http://www.medhelp.org/forums/Muscular-Dystrophy/show/1223
; so you definitely want to start a post over there.
However, one side effect of orapred is trouble sleeping. If your child is having trouble sleeping you definitely will see changes in behavior. Side effects are from here - http://www.medicinenet.com/prednisolone_solutionsyrup-oral/article.htm
This is definitely something that you want to discuss with your doctor. I can understand why this drug was prescribed, but it is a powerful drug and you should have been informed of its possible effects. Especially the effect on the immune system. Best wishes!