Okay, what type of links are you building? Are you declining in the quality of links being built? Have you invested a few hundred dollars on authoritative articles? A building business needs stronger sources. There's no explaniation for why this has happened but you must continue to build and re-invest back into your business. Example - Investing in having Apple or Yahoo write an article about your site, services or products.
Right now we're watching one clients pages slowly climb in Google, while another is being consistently beaten by a wholesaler with absolutely no content on their pages other than a small image and the name of the product, not even a price, description or sales/delivery information. If this is a result of the new Panda algorithm, and this is being replicated around the world, Google is about to come under a veritable sh*t storm of abuse from small businesses being beaten by absolutely no content.
I am so thrilled. Judging from the previous updates my website's overall ranking should improve since i haven't done any black hat techniques.