jbayabas - 3:42 pm on Aug 17, 2013 (gmt 0)
The real problem here is the big discrepancy in your page views which reflects in your big discrepancy in your clicks. I don't believe for a second that adsense's reporting is flawed or has a bug, if it were, many here would be up in arms defending you.
I firmly believe it has to do with your site. I'm sure even if you contact google, they will tell you to check your site. You stated you made "small changes" to your site prior to this big drop. Small changes could be a big thing in Adsense (ei. Adding the word "up" to "beat" is already a big difference as Adsense consider "beat up" stop words).
Are you sure you only change the colors of your site and did not add any texts to your header, footer, and widgets? Do not be so sure you do not have blank ads. Some of your visitors may be seeing your site differently than you.
Use pingdom to check if youre seeing Adsense ads on the screenshots. Focus on your secondary and old pages, not just the homepage. Use also google Adsense sandbox to see if ads are displaying on all your links.
My other suggestion is to revert to your old design/ layout / colors to see if it makes a difference.