Luzzu wrote: "As to the definition of a quack doctor, I think it is someone not qualified who pretends to have medical knowledge and who recommends treatments that are ineffective."
I think that is probably a good description of what it should mean. However, it is easy to imagine the term being applied to a doctor who was eccentric or incompetent, or who had a bad reputation for some other reason, but who was, nevertheless, properly qualified. That is why I hope you will check if he was licensed by the S.O.A..