Does anti-psychotic medication cause Parkinson symptoms such as mumbling when talking??? and tremors???? I started taking Benztropine to treat it, will it help me??? and how long i takes for it to start working?

A relative of mine is experiencing this and it is awful. I want to know if there is a light at the end of the tunnel.
Medical professionals are not giving answers and this has been going on for almost 6 months. The medication causing the psychosis has been taken off him but the psychosis has not stopped. He is now on anti-psychotic medication which makes his movement worse.