Perhaps the dose is a little on the high side. Moodiness and hyperactivity are potential side effects of prednisone. I'm sure your doctor feels the dose is necessary, but your son may be producing just enough of his own cortisol to tip the scales. I found some useful information in "A Parents Guide to Children's Medicines (page 131). http://books.google.com/books?id=FfxkFSlZAF4C&pg=PA131&lpg=PA131&dq=Children+moody+prednisone&source=bl&ots=kygLstHqg2&sig=I20oGvwpMBqKX_kqgMt3lpUOaFE&hl=en&sa=X&ei=-YNxUe-xEsSSiALx6YHQDg&ved=0CF0Q6AEwBg#v=onepage&q=Children%20moody%20prednisone&f=false

On another note...when my son gets "moody," I know it is an indication that he is having a flare. Something is going on inside that he cannot express/identify. I liken it (somewhat) to the hormone changes during a menstrual cycle.

In any case, it is difficult to sort out which is normal hormone swings, the disease and the medications. I hope you get it sorted out. I look forward to future updates.

Best wishes to you.