Doctor I Know U!!!

A young guy was feeling ill, so he asked a friend to recommend an internist. “I know a great one,” his friend said, “but he’s very expensive. He charges $400 for the first visit and $100 for each visit after that.”
The guy went to see the doctor. Trying to save money, he greeted the doctor when he entered the exam room with an animated “I’m back!”
The doctor proceeded with the examination. “Very good,” he said when he was finished.
“Just continue the treatment I prescribed last time.”