What to do if my child got sick? (Berlin)

Hello!
I have been in Berlin only for a week now, so forgive me if my question look very naive. I wanted to know what's the common procedure to do when children get sick, i.e. fever or high temperature? Should i head to the nearest hospital? or should i call the Protected content number? or should i call an ambulance?

I just wanna be prepared for any emergency case!

Thank you,