Help with google dance explanation?

Hey guys,

So I have been back linking and optimising my site for a while now and was up to around 200-300 organic searches a day but the past 2 days it has dramatically dropped to 50-100 and I see some keywords I was ranking for have now dropped either loads or off google is this normal I heard someone say it may be a google dance but I am not sure what this is.

thanks in advance