I had one of my sites drop in every niche except for two of them. I have a couple theories: 1) It is only 5 months old. 2) I did change the content in the body - but I didn't change the keywords. 3) I did change the keywords in the title tag - this is probably what dropped it. 4) I added another navigational link on top - probably didn't hurt it from my opinion. 5) I did change my backlinks to this site in some forums (took it out and then put it back in - I know...stupid). Anyone think of anything else? Also, I only dropped 40 in one niche, 8 in another, and 10 in another niche. Another question: To get my site back in the top ten - should I start backlinking again?
it is usual to see a drop in SERp ranking after a major change. and yes, yuo will need to start some link building which will help you get back up again