I'm pretty sure there's a good reason I haven't found an exact translation for psychologist into latin, but I was thinking something like: Medicus / Medica Aegris Animis. If that works or you have a better idea, please let me know!
EDIT: medicus animi (the doctor of the soul) sounds logical to me. If you need neo-latin expressions, a good source is the Lexicon Recentis Latinitatis.