Comic #5374: your-kid
Description
Here is the text from the comic, transcribed as accurately as possible:
Panel 1:
Doctor: "Now, before I start my exam, I want you to know that you know your kid better than I do."
Panel 2:
Parent: "WHAT?! Why am I paying you?! Pediatric medicine has been a thing for centuries and you just skipped it?!"
Panel 3:
Doctor: "You have 20 years of medical training! Were you asleep the whole time?!"
Panel 4:
Doctor: "Look, it's just a thing I say so parents think I'm not condescending."
Parent: "OH THANK GOD."
(Note: The comic is attributed to "smbc-comics.com.")