The symptoms suggest that your daughter might be suffering from Nephrotic syndrome
is a glucocorticoid used as an anti-inflammatory and immunosuppressive agent is used for treating the condition.
So...the medicine given by your doctor is correct.
Long term use may have side effects like increased susceptibility to infection, easy bruising, abnormal fat distribution in body, etc.
Symptoms aggravate if medication is stopped abruptly.
Make sure while discontinuing the medication, its dose should be tapered gradually instead of stopping it abruptly.
There is nothing to worry...continue the treatment as advised by the Doctor.
After completion of treatment, your daughter will be alright.
Wishing your daughter a good health.
Thanks & take care.