Article "137 real estate slogans" was on the 2nd position for "real estate slogans". Now it is not in the top 100. I din't do a lot of back linking at all - just a few manual links from blogs posts and comments only.
Other pages dropped in rank too.
The only change I recently did was installing a new WP theme "Vantage" ~ 10 days ago which has a directory module with reviews and rating. I was going to use it just for providing a free section for listings of resources for real estate agents. I put 5-6 of these listings with short 200+ words descriptions.
Yesterday I noticed the drop and the only warning on Google webmaster tools was that this theme generated ~ 100 links to non-existent pages inside the directory module. I cleaned that up but still no improvement.
Can a new theme cause something like this? Should I go back to the previous theme I had?