side effect for taking psychotic medicine

My wife is suffering from chronic schizophrenia since our marriage in 1999.
She was taking medicine since 2000. we have a son of 11 year old. My wife is also suffering from chronic asthma and thyroid problem for which she also taking medicine regularly. After passing though a difficult time of ten years now a days we are passing our most of days smoothly. Only few days are passing with little difficulty due to illness of my wife.

The problem is that sometimes the legs are becoming stiff. Now a days it happening frequently. For this reason she was crying and becoming impatient.

Why this is happening? The doctor said this is the side effect for taking psychotic medicine for long period. The doctor had prescribed some extra medicine. This problem is lessening a little but could not cure it.

She was becoming depressed and sad day by day.What to do? Please help anybody in this matter.