ken_b - 2:42 am on Nov 24, 2013 (gmt 0)
I took my ads off my site for 3 days during some site edits and since then my daily average is half of what it was.
This might e where the prolem started.
What did those edits consist of? Did you change the text, even a little? If so, you may e getting a different set of ads that are getting clicks that Google thinks are questionable for some reason.
Ember's point about ad location is worth looking at too, did you move the ads, or place ads with a different size/format?