A medical charlatan
A quack is 
a "fraudulent or ignorant pretender to medical skill" or "a person who pretends, 
professionally or publicly, to have skill, knowledge, or qualifications he or she 
does not possess; a charlatan or... [DOC] [TLE] Charlatan - Wikipedia [PAR] A charlatan is a person practising quackery or some similar confidence trick in 
order to obtain ...