Keeper my first thoughts are probably got pnuemonia or bronchitis or something like that, strange about a slimy beak, I would post it over on the thread i will post as it's for sick chicks and people that know more about it will be able to help you better.
https://www.backyardchickens.com/f/10/emergencies-diseases-injuries-and-cures
https://www.backyardchickens.com/f/10/emergencies-diseases-injuries-and-cures