Depression. In taking it for very long?

Since beginning of this year my father is facing depression. I have met many doctors for it. He is better than earlier when he meets other people. But at home, he keeps pacing around non-stop and gets very disturbed when anything breaks down around house . He gives up whenever he sees any problem even the simpler one. One has to literally push him to take outside for simple groceries purchase or to meet relatives. He was taking d-Veniz 50 mg twice a night. But we stopped it since past 15 days. Can he start taking the same amount of Medicine again? How long should he keep taking it? Is there any harm in taking it for very long? He was taking it since may end. Can someone please help as he is not ready to go to a doctor