Help understanding 有病不怕，只怕有病说没病，不肯让大夫治疗。
Haven't read the story for more context, but I would read it like this:

我该说的都说了。
I've said all I can say.

有病不怕，
Don't worry if you get sick,

只怕有病说没病，
just worry if you get sick but pretend you are not sick,

不肯让大夫治疗。
(and therefore) you don't let the quack treat you.

Boom, shortly after, clogs popped!