In all cases you will receive advice and help from the responsible youth welfare office and the addiction counseling centers.
Youth welfare Offices Berlin: https://service.berlin.de/standorte/jugendaemter/
Information on addiction counseling: https://www.berlin.de/familie/de/informationen/suchtberatung-und-suchtpraevention-122
State office Berlin for addiction issues: https://www.landesstelle-berlin.de/adressen/broschueren/sucht-drogen-rat-hilfe