Prednisone is often given to help with irregular menses and has been known to stop menses in those who use it regularly. It has also been known to jump start menses in teenage girls. I do not know its effects on menses after it has been discontinued, perhaps someone else here has an answer for you on that subject.
However, it is highly detrimental to stop prednisone without a doctor's ok - even then, you are weaned off slowly. It can cause serious harm if it is stopped.
Best of Luck
I wish you and your daughter Peace and Blessings