Most times, you wait forever for an appointment. Then you wait an hour in the waiting room. Then they at best tell you no more than you already knew. Or maybe they prescribe Amoxicillin for your child--which has long since become useless. Your insurance gets charged, you give your twenty dollar co-pay, you get your Amoxicillin knowing it won't do anything, you pay your five dollar co-pay.
This is really just a stalling game, to weed out the really sick from the wimps and paranoid parents. Doctors probably know, they probably talk about it. Sickness is normal human stuff. Giving medicine actually makes these little vermin stronger. You need to let the sickness just take its course for the good of humanity.
So really a second visit is the first real visit. Only then do doctors start to take you seriously.