Hi Cassie! You're confused because the author intentionally misuses the word in order to show that the quack doctor doesn't know what he's talking about. "Apothéose" means the high point of something (for example of a play or a career), with a more epic, majestic, glorious shade of meaning than, say, "climax".

In English, what the doctor is saying would sound something like "Yoghurt is excellent for your stomach, your kidneys, your appendicitis, and your zenith". Note that appendicitis in this context doesn't make sense either. Nobody wants something that's good for their appendicitis, because appendicitis is an infection. You'd either want something that's good for your appendix (the body part that suffers from appendicitis) or something that's good against appendicitis.

Hope that helps!