goodroi - 1:35 pm on Apr 22, 2013 (gmt 0)
Are you sure this is only Panda and not something else?
If you got hit in November, what have you done to improve the quality signals since then?
Google generally sets a low bar for minimum standards. Over time they like to raise that bar. What could be happening is that your weakest pages were hit first and as Google tightened their minimum quality standard, more and more of your pages were found to not be strong enough. I'm not sure that is what is happening in this specific case. I bring it up as a reminder that we should never rest and we need to keep improving our pages.