a fraudulent or ignorant pretender to medical skill.

a person who pretends, professionally or publicly, to skill, knowledge, or qualifications he or she does not possess; a charlatan.

being a quack

a quack psychologist who complicates everyone's problems.

presented falsely as having curative powers

quack medicine.

of, pertaining to, or befitting a quack or quackery

quack methods.

to treat in the manner of a quack.

to advertise or sell with fraudulent claims.