1) Buy a stock of Smarties, sort them into their different colours,
2) For effect buy a white coat (optional)
3) When the patient arrives give a dose of the yellow Smarties and tell him to take 2 -four times a day for a fortnight.
There are three possible results,
1) he gets better (What a wonderful doctor you are)
2) He gets worse, move him on to the red Smarties for two weeks.
3) He dies............If only he had come to you sooner.
If he survives all this refer him on to a specialist.