I didn’t want to hijack this thread, but it raised another question I’ve wondered about for decades. (Okay, not for every moment of the last 30 years or so, but it comes to mind occasionally.)
Some diseases/disorders get no article; some get a “the,” and some get an “a/an.”
A headache (tooth ache, stomach ache; an earache)
A nervous breakdown
Is there some pattern to this?