In all cases you will receive advice and help from the responsible youth welfare office and the addiction counseling centers.
Youth welfare offices in Thüringen: https://www.thueringen.de/mam/th4/justiz/schoeffenwahl/jugendamter_2018.pdf
Important information can be found here: https://www.suchtfragen.de/ and https://www.hls-online.org/
Addiction counseling centers in Thüringen can be found on the website of the Department of Addiction Prevention in Thüringen: https://thueringer-suchtpraevention.info/ansprechpartner/suchtberatungsstellen/