The key thing with a database driven site, is to be sure the same url is used each time a specific page is called, but also that they are all unique enough to prevent being de-indexed for duplicate content. I’m confident the recent drop in ranks is because the URL’s changed, but we need to work out how to get those ranks back.
Google obviously has noticed, they make billions every year by indexing web pages, their entire revenue streams rely on crawling and indexing web pages, they do it very well, so there is no chance whatsoever that they wouldn’t notice!
This is the reason why your site has recently dropped out of the search engines for the regional “stop smoking” search phrases. The fact that “stop smoking malburton” is returning a completely different page is proof of this.
The pages Google was previously ranking no longer exist on the site and for some reason the search engine friendly URL’s you had before have been replaced with dynamic URL’s instead, I can only imagine this is to make the site database driven.
Probably not what you wanted to hear, but this is the source of your drop in the search engines.