think i've read about this before and it happens to me often enough that's almost expected.
every time i post new content, even a page, adsense earnings drop almost immediately and significantly sometimes by 50%.
then they improve over a few weeks before they stabilize. but i fear some day it may never recover.
if i go months without publishing anything new, the earnings remain pretty normal and stable.
i almost want to leave my site alone and publish nothing new, ever.
guess if it's not broken, ...