Need suggestions on how to get someone in a catatonia state

My nephew had his first psychosis about four years ago. With the help of meds, he was doing pretty good. His psychiatrist decided to remove his antipsychotic med last month. Well he went through a breakup over a week ago and I guess that triggered his psychosis/catatonia state. He had stopped taking his meds altogether and stopped eating. He’s an adult so we couldn’t force him to go to the hospital, but after we called 911 a few times, the cops convinced him to get in the ambulance and go to the emergency. They gave him Ativan right away which helps get someone out of that state and it was working but since two nights ago he refuses to take the Ativan and his state is back to what it was and tonight he is refusing to take any med at all. His parents are with him trying to convince him to take them. I guess I don’t know what I’m really asking for, maybe some advice or suggestions on how to get him to take them including Ativan? 😞