Weird problem with Google. My site had a pretty good ranking until recently! These days some of my posts, get indexed pretty quick in google and rank pretty well. After few days its de-indexed for no reason whatsoever and after few days its reindexed. Unfortunately though, when its re-indexed it ranks much lower. What could probably be the reason for this? My site has unique original content, although quite a few times some sites have copied my content. Please help