People should be held liable for intentionally stating non-truths with respect to one's own, or another's character: ie falsely claiming to have a certain medical license.
Howver, I don't see how you can come to the conclusion that ordinary people should not be able to tell their children, friends, parents, or anyone, medical advice. If so, where does it end? Can you tell your child to take medication? Which medications? Can you help victims of accidents? Give CPR? Can you tell your Father not to get that particular medical treatment? Can you tell someone to not trust a particular doctor? What you're suggesting sounds like a litigious nightmare of egg shells through life.
On principle, should we not err towards advocating for granting power to the people instead of centralized, corporate and government authority structures? Or do you just not believe in that?